Amy, congrats on taking this big first step!
It is good to hear that it went great for you, and I hope everything works out well eventually as you want it to.
I was very scared too about my first session with a therapist nearly two months ago, but I had to talk to her as I was otherwise screwing up my mental and emotional health. She does not even specialize in gender issues, but she has taken everything that I've said very calmly, with no adverse reaction or prejudice, and has in fact helped me believe more in myself by telling me that I do not owe an explanation to anyone for who I am.