I sympathize with your frustration over therapy.
I don't know a secret for finding a poly-friendly therapist. The way I did it was trial and error. It was a long and grueling process.
I definitely recommending finding someone new rather than trying to make it work with your current therapist. I saw a therapist for 8 months who wasn't really helpful--but I felt too guilty to leave. I felt like I should try to make it work with her, like I was being a bad therapy patient if I just wanted someone to tell me what I wanted to hear.
So I wasted a lot of months getting nowhere (and, in retrospect, talking to her was making me feel a lot worse). Finally I quit making appointments with her and didn't see a therapist again for six months.
When I finally got the courage to make an appointment with someone new, I started out by explaining to her that I have an alternative perspective on dating, and that I hadn't been happy with my previous therapist because I had felt she was judgmental and unhelpful in regard to my dating issues.
That started the session off on a very positive note. My new therapist was very willing to approach my issues with an open mind. She admitted that except for one previous patient in an open marriage, she did not have much experience with polyamory or other types of non-monogamy, but that she was willing to learn.
The sense of relief I felt after just one session with her was enormously liberating. I have felt so much happier with myself since I started seeing her.
In retrospect, some of the things my old therapist had told me and asked me were totally ridiculous in relation to my situation. But for a long time I lacked the perspective and self-confidence to seek out a new therapist.
Anyway, that's my advice to you: find someone new and explain clearly what you want.
Single, straight, female, solo, non-monogamous.