I explained to her the feelings I have had since childhood and that I am seeing a therapist to deal with them. She was very supportive and cool, though worried. Her only resentment was that I had not told anything about it to her before.
She is worried that if I change gender I end up not being accepted by society, but says she will love me whatever happens. I didn't go into a lot of details about how I feel about my body right now, I am letting her process the info I gave her first. 🙂