How to know if my therapist can actually help me?

I saw my therapist for three weeks now, the first two appointments were mostly background stuff. I asked her if she was trained in trauma and she said yes. Today we really got into the meat of it and she asked what my mom was diagnosed with. I told her, and she apologized and said that's a bad one with a poor prognosis. I told her I have traits of it as well. She said she didn't see any indication of that. Then we changed the subject. But, yeah, I'm actually diagnosed with that. Soo...

I'm thinking it won't work because she thinks people with this have poor prognosis and she basically isn't expecting to help much. Am I overreacting?