I have only good things to say about therapy. Meds work well and combining those with therapy is the best course to recover from anxiety. Therapists can help you get to the bottom of triggers, give you ideas of how to cope, can be a good outlet for emotion. Good luck
There's no reliable statistics on most forms of therapy. A couple of double blind studies can be found on the NIH website on CBT, a form of anxiety therapy that is more standardized than other forms of therapy, and it worked about the same as meds -- 30% of the time. But statistics are misleading, because in therapy the relationship with the therapist and the motivation of the patient are most important and so if one doesn't work you can just keep trying. What is known is that there is no medication that cures mental illness, but many people do report getting cured through therapy. That's why docs used to send people to therapy before trying medication, particularly given that all meds not matter for what have problems. Also, all meds were approved only for minor to moderately severe depression, with a little bit of study added to get anxiety treatment added. Not many people were involved in these studies, they didn't last very long, and placebo did pretty well. Meaning, it's a tough problem to have as we don't know the cause most times, so not trying therapy just takes away one of the only known cures. Personally, therapy never worked for me, but I'm still trying. Meds helped, but also hurt. When therapy doesn't work, it doesn't hurt.
Since you re getting benefit from the meds, you might be able to make some progress with therapy. For lots of people the constant anxiety makes it hard to focus on the therapy so they don't benefit .