[RPG] What do a minotaur’s rations consist of, and can a dragonborn eat them

Strictly better? No.

One of the major points of Disguise Self is that it can not only alter your appearance (via illusion), but your clothing and equipment as well.

It's important to note the inverse of this: Alter Self does not specify that it modifies your clothing or equipment. This means that, depending on how severe your alterations are, you may no longer fit into your armor and your clothing may clearly no longer fit you, depending on how simulationist your DM is on the topic. This is especially important if using the "Variant: Equipment Sizes" rule on PHB p.144:

In most campaigns, you can use or wear any equipment that you find on your adventures, within the bounds of common sense. For example, a burly half-orc won’t fit in a halfling’s leather armor, and a gnome would be swallowed up in a cloud giant’s elegant robe.

The DM can impose more realism. For example, a suit of plate armor made for one human might not fit another one without significant alterations, and a guard’s uniform might be visibly ill-fitting when an adventurer tries to wear it as a disguise.

Using this variant, when adventurers find armor, clothing, and similar items that are made to be worn, they might need to visit an armorsmith, tailor, leatherworker, or similar expert to make the item wearable. The cost for such work varies from 10 to 40 percent of the market price of the item. The DM can either roll 1d4 × 10 or determine the increase in cost based on the extent of the alterations required.

Even if your equipment does fit you after the effects of the spell, any well known gear or accessories may still let you be identified, especially if they're more well known then your actual physical attributes.

There are a few other considerations as well.

One of them is that both Alter Self and Disguise Self can be used at the same time, to enhance the illusion with actual physical changes underneath it. Do note that this is only possible because Disguise Self does not require concentration, which is another point in its favor over Alter Self, which does. This means Alter Self can fail earlier than intended (especially in combat or while under stress), while Disguise Self will last the duration under most conditions, and still allows you to cast other concentration spells.

Another is comparing how Disguise Self and Alter Self interact with height & size.

Alter Self actually changes your height, while Disguise Self only creates the illusion of a height change, keeping you your usual size. This might matter if your DM actually cares about character height in certain situations rather than just your size.

In addition, Alter Self restricts you to only changing your appearance to a creature of the same size with no other restriction on maximum height gain/loss, while Disguise Self only has a restriction on height change rather than size change.

For example, with Alter Self, you could change the shortest possible dwarf into the tallest possible goliath, whereas with Disguise Self, you could make a dwarf appear to be a halfling (so long as you're not trying to change your height by more than a foot in doing so).

Overall, I'd probably rate Alter Self better than Disguise Self in some combination of the following situations:

• There is plenty of time to make preparations in advance, including having an appropriate alternate outfit ready.
• You are unprepared, but you only need minor superficial changes with no drastic change such as size, making the lack of alternate costume not an issue.
• You are in no danger of having your concentration broken for the next hour, nor are you likely to need to cast any other Concentration spells.
• You are likely to be thoroughly inspected for some reason or another.

In other situations, there is a chance Disguise Self may be the more appropriate spell. In a situation requiring an emergency drastic appearance change (clothes, size, and all), for example, I would much prefer Disguise Self as my option.

"I am having fun this way and I'm not a liability to the party so there is no problem."

From what I can tell you're going with a character who's more about support spells rather than outright damage spells. Which, given your good charisma might actually be a very good choice. But there's two sides to playing D&D: the combat and the roleplaying. So you need to ask yourself this:

• What do I do in combat? Your build is not one of setting everything on fire, but you still have to do something to not be a liability to the party. If you have considered this, and thought about what you do if the monsters no-sell all your Suggestions and Charms, you should be fine. This is important for all characters by the way: what happens if your main thing does nothing against the enemy.
• What do I do out of combat? As a character more geared towards roleplaying you should have a leg up in non-combat encounters. Make sure to point this out to the party and ask them how they deal with non-combat situations. Do they have spells that can do this? Do they have skills and high charisma to smooth-talk their way around? If not, well there you have it. If they do, selling your character is a bit more difficult but still managable.

Just remind them of the fact that if you're having fun and not a load to the party, they don't have a leg to stand on when critiquing your choice of character.