You retain control over your character.
I'll make three arguments for why:
RAW
The text of polymorph does not make any mention that you lose control over your character. It also does not say that your goals or personality are replaced by the creature's - only your intelligence score. Thus, you are still the same person, just with sharper teeth, fins, and a less smart brain. If your GM is dictating that a character with an intelligence score of 2 can only be an NPC, your GM is creating a house rule to do so.
Verisimilitude
You retain your personality and memories, and there's no reason why your shark-brain would suddenly forget what you planned to do. An intelligence score of 2 is not so low that you don't remember you're not a shark, and sharks have a non-negligible wisdom score, so they aren't slaves to instinct. You would still remember being a wizard. You'd remember turning into a shark, and you'd remember what you planned to do. You might not be able to think back and understand why you made the plans you did (nor would you be able to come up with a new plan easily), but you'd remember that your wizard-brain is a lot smarter than your shark-brain, and you have no reason not to trust yourself to have your best interests in mind.
Group Dynamics
I do not believe such a house rule is a good idea. That ruling means either, "I do not trust you to play a character with an intelligence score of 2" or, "I don't like that you're using polymorph and want to weaken it." Neither leads to savory group dynamics.
If your GM doesn't trust you to roleplay your characters under anything besides ideal conditions, that's his problem. He is no more qualified than you are to play a character with such a low intelligence score, and you know your character better than he does - thus, you're more likely to know what your character would do in a situation, even if that situation includes "and they have a low intelligence score.
If your GM doesn't like you using polymorph to solve a problem that polymorph is perfectly capable of solving, he should bring that up outside the game - not deny it midstream.
It sounds like whatever you want it to sound like. As you say, RAW is only:
You gain the ability to comprehend and verbally communicate with beasts for the duration.
Breaking this down you can comprehend their verbal and non-verbal signals and you can only "verbally communicate" i.e. talk to them. The simplest explanation is that you each speak in your own "tongue" but the Magic makes this comprehensible. However, if you prefer, you speak in the native tongue of the animal. Or you each speak in a mutually comprehensible ur- language. Or an angelic/demonic translator appears. Or ...
Best Answer
Yes, it is possible.
The problem is Feeblemind killing the target beast, but it is easily overcome.
Simple way would be to cast Death Ward on target animal. It's a non-concentration 4th level Cleric/Paladin spell, with duration of 8 hours, so it should be easy enough to arrange at the point you have Feeblemind and Awaken available. That will make it drop to 1 hit point when any damage would drop it to 0 hit points, so casting Feeblemind is now not deadly.
If you can't arrange Death Ward, a more messy alternative is to give temporary hitpoints, for which Enhance Ability for Bear's Endurance, max 12 temp hit points (2d6, but it's a 2nd level spell so you can easily try several times) might be best as it is free to cast yet can give enough HP to make survival likely. But better prepare to lose a few beast specimens before one survives, if you go this route.
Once the target survives the Feeblemind, direct reading of Awaken says it is a valid target:
vs Feeblemind instant effect:
Then there is the remaining issue of Feeblemind staying in effect. Feeblemind is a reversible state, which is probably not overriden by Awaken. But this is irrelevant, Feeblemind effect needs to be removed anyway. Now the question is, what is the beast's INT after this? If an originally INT 3 beast is awakened, feebleminded and dispelled, its INT would clearly be 10. If order is Feeblemind, Awaken, dispel, there isn't any reason I could find for the order to matter, final INT would still be 10. So, same would apply if the original INT was >3.
Feeblemind should of course be removed before its next saving throw (every 30 days) to avoid the need to even consider what would happen, if that save fails. I'll asume this is not a a challenge for characters able to cast Awaken and Feeblemind.
The only caveat really is, that Feeblemind is reversible, so the original INT score must still be in existence, and a DM would be within their right to rule that this original score (in the creature's stat block) is what Awaken looks at. But this is going beyond what is actually written in the rules, and would be very strange, since everywhere else "ability score" means "current ability score" without needing to be explicit about it being "current".