Looking at this handbook (2010), (Be advised that he uses an unusual colour scheme, for people used to modern handbooks.) we can see some general patterns:
At the end of the day, you'll be looking for ways to bypass it. The two power that you should have, therefore, are Crystal Shard and Amethyst Burst. Nice, low-level powers that can be augmented well. Crystal Shard is a ranged touch attack (with all the ways that that can be cheesed). And Amethyst Burst is nice as an AoE.
The general pattern is: find the no-save, no-sr powers that are most compatible with your party, and take... them. Use the rest of your powers on doing Cool Stuff. Have your signature no-save, no-sr (probably ranged touch, though telekinetic thrust, with the right optimization can be cute), and have your backup no-sr, no-attack. In high epic, the game is silly. You should be focusing on "dirty tricks." Either doing the scry & die game with the opposition, or preventing insta-death teleports from happening to you.
You may want to focus on appropriate astral constructs. It's one of your signatures, and summoned monsters, when appropriately optimized, can be incredibly useful. Consider specializing in it with an appropriate PrC.
If you're really playing silly buggers, embrace taint (and the necessary hooks to ignore it), and grab Subverted Psion. That, combined with Thrallherd means that your evil army (all armed with appropriate magical devices of no-save no-sr powers), can just kinda swarm the badguys.
Pay especial attention here, where the optimizer breaks down some of the better choices:
Ranged Attack Roll
Any power you select should preferably be a ranged touch attack. This means rays and the like. In this category, three powers stand out: Crystal Shard (Psion 1), Entangling Ectoplasm (Psion 1), and Crystalstorm (Psion 2). What makes these powers superb choices is that they all fill two other roles: they don’t allow a save (note that Crystalstorm does allow a save against its secondary Con damage effect, but not against its primary HP damage effect), all are instantaneous creation effects and are thus effective in Anti Magic/Null Psionics fields. Finally, none of them are subject to SR/PR.
Ranged attack roll: Crystalstorm (Psion 2), Disintegrate, Psionic (Psion 6)
Melee attack roll: Astral Construct (Shaper 1)
Targets Fortitude Save: Disintegrate, Psionic (Psion 6), Energy Wall (Psion 3)
Targets Reflex Save: Energy Wall (Psion 3), Amethyst Burst (Psion 2)
Targets Will Save: Time Hop (Psion 3)
Allows no Save: Crystalstorm (Psion 2)*
Not Subject to Spell Resistance or Power Resistance (SR/PR): Crystalstorm (Psion 2), Energy Wall (Psion 3), Amethyst Burst (Psion 2)
Area of Effect (particularly for fighting Swarms): Energy Wall (Psion 3), Astral Construct (Shaper 1)**, Amethyst Burst (Psion 2)
Force Effect (for fighting Incorporeal/Ethereal creatures): Amethyst Burst (Psion 2), Astral Construct (Shaper 1)**
Effective against Anti Magic Field/Null Psionics Field: Crystalstorm (Psion 2), Amethyst Burst (Psion 2)
Effective against Globe of Invulnerability: Disintegrate, Psionic (Psion 6)
Creating epic psi powers causes sanity loss, but given that they work like normal peic powers, look around for an epic spellcasting guide and plagiarize. Considering that you'll certainly have thrallherd and/or appropriate leadership chains, you'll have plenty of assistance.
Beyond this, given that you're in a stupid-optimization game, consider:
There are a number of infinite action tricks there. I am especially amused by the save state trick. I would also ask to become a erudite with spell to power. Cause why limit yourself to only psionic tricks?
It's very difficult, but pretend like you're an unskilled bard and take a first level dip into something more survivable.
To be clear, much of your survival, even more so than normal "quadratic" classes, will be a direct result of your personal creativity. Don't engage in fights you don't have to, be liberal in your sneaking about and talking-people-out-of-things. Make your first level dip and your creativity carry you through. Read the commoner handbook to get you into the right mindset.
I was halfway through writing up an answer discussing how totemist and beguiler are excellent 1-2 level dips for a dual-casting progression career when I was reminded of one of the sillier rules of the erudite:
Exception: If a character with erudite levels gains at least as many levels in another psionic class as he has in his erudite class, he permanently loses the ability to add additional powers (above and beyond the two gained at each new erudite level) to his repertoire of powers known.
Which means that there's no dual-classing progressions allowed, and that first dip won't grow with the character.
First, then, consider a rogue or factotum/1 dip, Even though it won't grow, it'll give your character a fantastic basis for skills, allowing him to serve as a scout for the first few levels.
Consider also being an Elan (as Erudite is a variant Psion, there shouldn't be any trouble for favoured classes.) Being an aberration and having access to alter self provides a huge amount of very... odd... forms for polymorph abuse.
Consider instead being a Warforged. Repair light damage is available at level one with Spell-to-power, and when combined with adamantine body, makes you a veritable tank.
Your main objective is to convince your party that you're not a wizard. Wizards are, by definition, tiny gods. That is due to the scope and versatility of their powers. Your character plays much more like a spirit shaman: you can choose, on any given day, to specialise in any given thing. In a normal game, this would be countered with much of your normal "casting" duties being offloaded into items. However, since you've stipulated your game is resource poor, this is out of the question.
At the end of the day, if this is a resource poor game, your erudite is going to be really suffering. Learning all of those spells from the minds of casters will require huge amounts of time and/or money. It's the archivist's challenge, but in a much more restrictive package.
Assuming that you do dip your first level, you do have a few useful things on your side. Spell to power is any arcane spell not simply any sor/wis spell. Therefore, look at the factotum handbook for all of the awesome spells that bards, assassins, hoardstealers, etc.. get. It will be a very tedious search, but odd-entries into early spells open them up for you.
If you don't go warforged, your first psionic feat should be a crafting feat. Here, much like the artificer, you simply cannot afford not to have emergency powers on hand. It'll consume much of your resources, but having rare spells on hand to cast when you need them is key to your staying alive to be awesome.
For example, your primary weapon for the first few levels should be your self-trained warhorse. A light horse is 75gp, but can be trained into a light warhorse with time. Hoof hoof bite on command for 75 gp is ... not horrible. Read the handle animal guide and pretend you're a druid. Given that, with time, you can apply the "warbeast template" to most any trainable animal, (Mind you, these are 3.0ish resources, but should provide an idea for how you should go about approaching the problem.)
Best Answer
From looking at your group I would put my chips on the problem just being that the psychic warrior is optimized while the rest are not.
In a brute force manner you could do the following, but I do not recommend any of these:
Since none of those solutions will solve the problem in a fair way I would recommend is tuning the game to give everyone a chance to shine. A few examples:
As a final note, your campaign is still in the very early levels. Eventually you will likely find that the Wizard and Cleric will start outshining every one else, that is just the nature of D&D 3.5. This is an idea called Class Tiers, which says that some classes are just better than others because of their raw mechanical power and versatility. This system does however rely on all characters being played at an equally optimized level, so if the one character is much more optimized than the others then this may not apply.
TL;DR Don't just try to buff or nerf the encounters or the party. Try to include situations where each character can shine, including outside of combat. The problem may just resolve itself in time as some characters become more powerful than others at higher levels.