What if even the anxiety you classify as 'mental illness' is also instinct, just with an unknown purpose? What if it's not an illness at all, just a misunderstanding? What if the anxiety is coming from the same place as intuition, or as part of it?

Obviously I don't know what you deal with, but it seems like you are very self-aware and have put a lot of thought into the matter. I only suggest exploring this other perspective because I think the words you choose to tell yourself about yourself are important. Your body will respond to what you say about yourself, positive or negative.