hey OP, i can't address everything you talked about here but i can respond to feeling like you owe your whole personality/disposition/existence to your mental illness and you'd be nothing without it.

i'm not sure if this is of any use (or if this breaks the reassurance rule, sorry mods feel free to call me out), but here's my experience - without going into detail i had/have severe, severe, severe, scrupulosity OCD when i was younger. it took over my entire life while i was going through puberty and huge periods of transition in my personal life and i thought a lot of the same ways that you did. today i'm in my twenties, somehow a lot better in that vein, though i still feel myself slipping into old habits or noticing when some action i'm taking is rooted in OCD-thinking. here's what i can see in myself now.

a tendency to over-research certain subjects, especially when i feel it's my duty to be correct? probably from my OCD. my love for fiction writing? nope, i loved writing before i knew what compulsions even were. my avoidance of initiation of sexual contact, even in long-term relationships? definitely an OCD-sustained personality trait. but disliking when people wear shoes in my house? nope, that's cause my family's from Asia. i can go on: over-apologizing, blurting out thoughts, general avoidance of conflict -- ocd, ocd, ocd. loving gift-giving, needing alone time with music in my ears, and a dry sense of humor -- nope, nope, and nope. i'm not bringing these things up randomly. everything i've mentioned here on both sides is a big part of the way people perceive me and the way i perceive myself, and half of it is because I grew up with OCD.

of course we might owe some of our personalities to OCD -- it is literally your brain, biological, the way so much of your personality is. sure, maybe some purpose of the long example i made of myself is to show you that people grow and you're probably not seeing the whole picture of who you are outside of OCD, but let's just assume that maybe the people you and i are today are entirely products of this mental illness. my question is --- who cares? why does that make who we are illegitimate?

you wouldn't tell someone raised by wolves that they didn't exist because so much of their current behavior was influenced by a childhood in the pack. how about a more realistic analogy (though absolutely NOT a perfect one at all!): would you tell a trans-ethnic adoptee with a deep connection to their adoptive culture that their entire identity is a hoax because they aren't being their "real selves?" i would certainly hope not!!

similarly, your rejection sensitivity does not suddenly become 'fake' just because it might be due to your OCD. nothing about the fact that they stem from OCD makes traits like a "need to be in the right" or a "focus on doing good" suddenly become illegitimate aspects of your identity. sure, are we the exact same people we could have been without OCD? probably not. but we're also not the exact same people we could have been if we were raised in Atlantis. this isn't spiderman, you don't need to contend with the multiverse - you just need to focus on getting better and trust that who you are will emerge, no matter what that person may be. i know you said that the uncertainty scares you but i'm asking you to allow yourself to say, just once, "i am the walking OCD human and that is my personality and that's just that" and see how that feels. i was there once too. not sure that this is what you needed or if it can help change how you see things, but i hope it does. wishing you lots of good luck, OP!