Impostor syndrome

I am a life coach and my niche is women who overeat emotionally. This is something I myself overcame and I believe Im very good at what I do judging by my clients’ progress and the way my business is growing. However, my latest clients’ stories resemble mine and Im “feeling their feelings” so much that it has triggered panic attacks and lots of anxiety. Also, I think Im going through impostor syndrome. (“someone will find out that I am not holding the space”) that Im considering changing my niche. A therapist suggested I’d be better off in a less “involved” niche but this is what Im good at and I dont want to act from fear. How can I believe in myself hard enough and stop doubting whether I should go on?