Hey,

I'm sorry, that's rough! I had a somewhat similar situation with my therapist where I felt he was invalidating my gender identity. He isn't a gender specialist and he did have a hard time grasping some of the things I was saying (I believe). I wrote him a long, jumbled letter trying to explain, to him as much as to myself, why his behavior made me feel so bad. I was close to leaving at that point. But following the letter, we had a good session and were able to straighten things out. Before I felt that like he was constantly questioning my identity (although I suspect that there was also some transference going on at my end). This has improved a lot.

Do you trust your therapist in general? If you do and would like to continue working with her, try to explain how she made you feel. Maybe try a letter if you think speaking to her doesn't work. Otherwise, would it be possible for you to find a different therapist or counselor?
Can you provide her with some resources on the topic that have helped you to better understand how you feel? Maybe she is willing to educate herself a bit more?

Could you try to find a trans* self-help group where you live? (sorry, I don't know which country you are in and whether this is even an option).