Did you have sex re-assignment surgery?
That's the first thing you ask? What her genitals look like? I think the better thing to ask/say is "are you fully transitioned," because my limited understanding of trans issues tells me that it's more than just sex reassignment that's in play when talking about how the physical body meshes with gender identity... but I could be wrong. I guess I have no claim to be personally offended here, but asking what's down below strikes me as a pretty personal question; I always saw it as running the risk of sort of fetishizing a person and reducing one's identity to their sex organs. Plus, whether a person even feels like they need such a surgery to express their gender freely and confidently is probably complex and not something they should be cornered into explaining.
Anyway, best of luck with everything, CrabCake.
I'm sorry I got a bit carried away above, lol.