I can tell you about my own experience - because it's the only experience I have in seeking a therapist
When I decided to start therapy, I looked around online for therapists on my insurance. Psychology Today has a pretty good search engine, with pictures and little blurbs from the therapists. I e-mailed the one I was interested in, and he did e-mail me back. We eventually talked on the phone- I liked him, but sort of put it on the shelf for a few months.
When I realized that I was really going to HAVE to go to therapy, I contacted him again. I also called another therapist. They both called me back fairly promptly. I was really torn between them - but the first guy I called basically did therapy on the phone with me while I was stuck trying to decide (he helped me explore my feelings about the two therapists I was caught between). In the end, I chose him.
I wonder if summer is a hard time to reach therapists? I know that a lot of people on here seem to have therapists who have been on vacation a lot lately (like mine is right now). I'm so sorry no one has called you back yet!