Not really an 'illness' per se, but I've got an autism spectrum disorder. Much less obvious than it was when I was a little kid, but still there. (I get really embarrassed and upset whenever I think about it for too long.)
I might have depression, or at least something in that area - I'd be third-generation bipolar if I
did have it, and there's an aunt with borderline.
Oh, and gender dysphoria of course, but that comes and goes.
I'm not okaaaaaaaay...