pop91 : My brain tells me that I was meant to have a flat chest and dick but I didn't have those so that caused me distress and gender dysphoria.
This may seem an odd question, pop91 , but who or what is this 'me' that apparently owns your ('my') brain and is told such things by this brain? Further, how does your brain tell you stuff like this? Have you ever thought that maybe you mishear (misread? -- anyway mistake) what you think your brain tells you? What, I wonder, is odd about such questions?
... I suppose you mean nothing more than that you think (feel?) you were meant to have a flat chest and dick. Talk of 'my brain tells me' may be a relatively harmless metaphor. Saying this, and thinking of it, the way you do, though ( 'my brain tells me' and so on), predisposes you to think you are something that exists independently of the body of which your brain is a part. And so off we go with the soul or gender identity and so on.
It is difficult to get your head round this (another metaphor!), I know. Our understanding gets 'bewitched' by the way our language works, as a famous philosopher once said. But do have a think about it all ...
Again, who or what is this 'me' that my brain talks to? (Writes to? ... sends pictures to? ... communicates telepathically with?) Is this 'me' ( 'Am I?' ) a physical thing? Non-physical? Or what? How is this 'me' related to the walking, talking human being that lives my life? And so on.
If you think about this, you might see that this soul thing is illusory. But that, of course puts paid also to the idea of 'gender' as something you have which is independent of (biological, bodily) sex. This strikes at the basis of your ideology, I know. Still, do have a think.