Even if these thoughts are "motivated cognition" as far as I can tell there's not any cure for them. You can view surgery and/or HRT as a palliative answer for not hating your body.

Many of the trans women and most of the trans men I've known are okay with their primary sexual characteristics. Women's T-shirts reading "I heart my penis" exist for a reason.) My sample is rather biased toward the less-than-binary, but still it goes to show that this isn't rare. BDD looks social, not physical, to me but I'm not an expert. (Not that social dysphoria is irrelevant, anyway.) I'm in a similar boat as yours. What I recommend is: * Don't panic. Litany of Gendlin; whatever your true gender (defined as the gender you would be happiest living as, to appease the anti-essentialists) turns out to be, it's already itself and knowing it will make you happier than denying it or making something up for the sense of closure. * It's okay to be whatever you turn out to be. (Yes, even "someone who guesses wrong and tries to live as the wrong gender for decades".) I never really had a problem internalizing that but Internet strangers telling you it's okay seems to help. * Try it on for size! Use text-based support groups, with people sufficiently open-minded that they'll happily comply if you tell them you're trying names and pronouns to see how they feel and change those every few weeks. * You've probably tried all the things you can do in private with no medical intervention (with clothing and hair and changing your apparent body shape and posture and so on). If it's feasible for you, maybe try to do them whenever you're in private for long enough that it becomes routine, and see how it feels when it's not an extraordinary thrill. * Some subsets of the trans community are binarist essentialist judges of Who Is Truly One Of Us. Avoid those. * Share your anxieties. I don't know if that'll help you, I just want to feel less alone.