I know a lot of you already told everything about that issue, but let me share my experience:
Some years ago, like, 4 or 5 years ago, I decided to look for a therapist. I already knew why I needed one and what I wanted to discuss. I had been in a dark place for years and knew about my gender issues for a long time already.
So, i found myself a therapist, but not a gender one, cuz I didnt knew that they exist at the time. My therapist was a great guy. It only took me 3 sessions to tell him my gender issues. But, to my surprise, he said that he didnt had any experience with gender issues but said that he would read about that.
So, i continued my sessions with him. Despite the fact that my gender issues were the primary matter that drove me there, it was NOT the only one. I was depressed, going in and out college for more than 10 years, etc etc etc. We talked a lot about all that, and he was great on that. But everytime we got on the matter of the gender issues, i could see that he was lost and even kinda uncomfortable.
Bottom line is: I saw him for about 2 years, and yeah, he helped me a lot, I'm a much less darker person. But, when it comes to gender issues, he didnt help much, even when he tried.