To me the brain structure stuff, etc, however it turns out, is pretty much irrelevent when considered in the context of how trans people of both genders, and other variations, actually feel, how they behave and how they identify.
Gender is mostly a construct and they vary through the ages, but the construct people choose is pretty much hard-wired into us from an early age. Intersex people and the way they have been abused by medical science teaches us that gender identity is innate. Studies carried out on young children also show that children know exactly what gender they are from about the age of 4 - including trans children.
Plenty of trans women barely change their appearance and tend to wear androgynous or even masculine clothing because thats how they feel most comfortable. So no gender stereotypes being reinforced there. Not more than many cis women do already anyway!
Trans people are as varied as varied as cis people. We do not reinforce gender stereotypes we merely do as everyone else does, choose the one that suits us best!! It helps to stop us getting beaten up for one reason and in my case my depression has stopped now that i can stop trying to act male and pander to male stereotypes, and people accept me as female.