How to discuss gender identity with therapist?

A therapist should not reject you. That's kind of their job. However, not all therapists are good and it could happen. In that case, at least confidentiality rules mean she shouldn't out you to anyone else and you may be able to file a complaint if she does. I have no idea of specifics on this, not being from the US myself -- your therapist should have information about confidentiality and such for you.

Even though you don't know whether this therapist is trans-friendly, I would recommend coming out to her unless you feel unsafe doing so, in which case I would recommend finding a new therapist anyway because you should not feel afraid of rejection or bad consequences from your therapist. If you are always holding back this issue, therapy will not work for you as well as it would otherwise (and if you are afraid of your therapist, therapy might not be effective at all). And your therapist may surprise you with acceptance and knowledge. Regardless, she should make an effort to be understanding and educate herself, even if it takes her a few weeks at first (though you should definitely feel free to find a new therapist if you are not satisfied with her reaction).

By telling this therapist and giving her a chance to react well, you may be able to keep and strengthen the relationship you have already built with her rather than having to start fresh with someone else. If you do need to switch therapists, that's okay and you'll make it, but I think it's worth seeing if this one is good too.

 

I agree with everything Dachs said and just wanted to say that I think it's unlikely that your therapist would react badly to it, I was worried how my therapist would react but she reacted good!
good luck!