This has been the second time in as many sessions that I had the perfect opportunity to bring up my gender with my therapist, and then didn't do it. She's really nice and easy to talk to, but I can't make myself that vulnerable around much of anyone. Any advice would be greatly appreciated.
I struggled with this issue a lot, and still do. When it comes to interpersonal communication, I am extremely reluctant to share sensitive and personal information. It almost feels like, whenever an opportunity arises to open up to someone, my throat fills with sand. The only times I told people about my gender dysphoria was (a) my parents, in a letter which took me 6 months to write and (b) the therapist that I was subsequently sent to after coming out. I hated therapy, and the therapist my parents had put me with made me extremely uncomfortable and didn't apparently know anything about transgender people. Most of my experiences being vulnerable with people have caused me a lot of pain. And as a result I isolated myself, for years. But sometimes it isn't all bad. Find a method where you can comfortably explain your feelings. When I told my oldest brother I was trans, back 2 years ago, I showed him a YouTube video which essentially explained it for me. During that time I regained my composure and was able to talk a little better. But even then, I literally had to force myself to spit the words out. It was scary as all hell but the relief was worth it, and the feeling of someone accepting you is inexplicably good. There will be mixed reactions. Sometimes it won't be easy to talk about it and be vulnerable, sometimes you will be rejected and hurt for it. That is just a fact. But sometimes something beautiful happens as a result. My advice: be brave, be patient with yourself, and don't leave any room for regret. The right time will come and when it does, just do it. Put yourself out there, breathe, and let go. You don't have to carry these burdens alone. There are people who are trained to help you sort through this stuff (e.g. therapists) and also people who love you and genuinely care about your well being (e.g. friends and family) that you can talk to.
I've never talked to a therapist in my life, but I know exactly where you're coming from. I'd just say that this person's job is to help you and the only way they can do that is if you give them the information they need.
