She is a woman, regardless of what's between her legs. Her identity is most important, especially if you'd be in an intimate relationship with her. Also, she will probably put in as much effort as possible to pass as a female and will appear feminine to you. Attraction to feminine traits, or those associated with the opposite sex, is heterosexuality. Accept trans women as women even if they aren't very far in their transition. Otherwise, don't ******* date them.