Girlfriend issues...

So I'm currently in a relationship and we are close, best friends first before we got together, been friends for 4 years and started dating just over a year ago. She is completely uncomfortable in her own body as she wants to be a guy (I respect that decision) but when we have sex she does everything I just lay there (enjoying it) but I wish to please her. I've mentioned this a few times to her but she just pushes the question aside. Is it because she's uncomfortable in her own body, but then why would she wanna be completely naked around me... She's my first proper girlfriend and I don't wanna lose her, but we should be able to please each other right?