Agree. Take a look around the web and see if she has any kind of online presence, or perhaps reviews from other patients. And regardless of whether or not you find anything, I would email her back and let her know that you're seeking treatment for gender dysphoria.
There are still a lot of therapists out there who have never encountered a trans person and won't have any idea how to help us. If she's willing to learn and work with you, that's great. But it would be best for you probably if she already had some experience working with other transfolks so that neither of you is going in blind.