I don't know what they'll ask or talk about, but I kind of want to be prepared. If anyone else has seen a (gender) therapist, what did they ask, or talk about?
I've seen a number of therapists, though not for gender identity. The first session is a lot of background and information gathering. It will help get you and the therapist on the same page so they know what you're looking to work on and how you got to where you are.