You're worried about what she might think. Can you ask her what she thinks? That way it is out in the open and you aren't worried about your speculations. Then if it turns out she does think this is a phase, you can educate her on that. I'm not sure why she would think it was a phase, though? Do you think you are communicating some ambivalence about your identity that would result in her thinking this is a phase?

I think she sounds like a good T and your relationship has deepened now that you have been more open with her. She seems to be trying to learn about you and your issues. So far, so good? If you feel you might need more of a specialist, could you discuss that with her too? She might have some good insights on that.