There's no "choice" in being trans, any more than there's a "choice" in being gay. People who are trans have an internal representation of their gender that is different from what their body presents as. That is a psychological condition - an attribute of their mental state.

Passing isn't recognized as a psychological condition because it isn't a psychological condition. Passing is making a decision to adopt the culture or presentation of a race that doesn't correspond to your internal model of what your race actually is.

Gender is a social construction, as is race. Gender is the rule governed behavioral manifestation of social and cultural expectations attached to observable physiological differences, as is race. Those biological differences may matter scientifically, in terms of reproductive function for sex and a variety of mostly insignificant morphological differences for race. Ultimately, though, the meaningful differences within categorical dichotomies like gender and race are social and not biological. The differences between women and men are not rooted in the presence or absence of testicles and ovaries, but rather in how we take these observable differences and go about establishing values, mores, and social structures that shape human behavior and social relationships around those differences. Since the underlying biology that is the basis of these social inventions matters only as a justification for their invention as traditions and the power inequalities those traditions establish, the claim that trans people have some "internal representation" of gender that is inconsistent with their biology is essentialist nonsense that reinforces the gender dichotomy and the sexism in which the dichotomy is rooted.

Being trans and/or being homosexual is not a revolt against nature, as your construction suggests. Rather, it is a rejection of naturalized dichotomies, dichotomies that are rooted not in nature but society. Being trans or being gay is a choice. It may be an unconscious choice, as is my "choice" to be a straight cis-gendered person, but a choice none the less. It is a choice because gender and sexual identities are social and cultural constructions, not natural expressions of biological essentialism. The way to address the psychological trauma of these dichotomies, be they transgressing assigned gender roles or passing through established racial barriers, is not to give permission to move between the poles of the dichotomy, but rather to explode the dichotomy itself. Exploding the constraints of gender categories means ending the inequalities on which those dichotomies rest.