Is it possible to be a good chess player without theory? I would like to be a very flexible chess player as in never in a uncomfortable position unless I did something to deserve it such as a blunder. I've concluded that the only way to do this is to avoid as much theory as possible? I feel like I might rely too much on theory these days (is there a way to tell if I really do rely on theory too much?) and would like to make a change but I'm not sure how to go about it.
Well, depends on your definition of theory and good. If you mean, never really studying specific things then you will be lacking in a few areas. Notably:


Openings. You will struggle at a high level without theory unless you are Magnus Carlsen. Most top level Grandmasters have memorised thousands of opening lines, and understand them extremely well. If they did not know these, they might be able to work out the correct answers, but they would use a lot more time to do so (which would be a very significant handicap). The computer age was leading towards theory being critical for most games, but Carlsen plays many novelties, showing that opening theory is not completely necessary.
Endgames. You might be able to work it out for yourself, but again, you'd have to be a super genius to naturally get this at a top level. Endgames have many specific things that would be much easier to learn if you just studied the theory. Without theory, it will take you much longer to learn the same thing.


There are probably more things. However, there are things that you can gain without theory:


Tactical Sense. Tactics don't technically have much theory behind them, as there isn't a HUGE amount of concepts to learn (pins, skewers, etc). It just requires you to improve efficiency in your brain, and calculating power. This is easier said than done, without a good position, you'll find that you don't have many tactical opportunities available to you.
General game sense. If you don't use much theory, and alternate your openings, you will probably be more versatile. Also, until a high level (>2000), you will trip up your opponents because you'll be playing off-book.


If you're looking to avoid theory (which I do), just alternate your openings! Have a cycle between your openings. Each game as black, alternate between c5, d5, e6, c6, etc. Don't choose too many, just pick ones that suit you. If you want to play quiet games against e4, play d5 or c6. If you want more intense games, e6 or c5. It mixes it up, and you learn the different plans for different openings.