When is it time to see infertility specialist?

My OBGYN is great, but how do I know when to see an infertility specialist? Can OBGYN test for hormone deficiency and other factors that can cause infertility? Recently, he has put me on clomid, but I am fearful clomid might not help in the long run. This is my second round and I read on Glow that after three rounds of Clomid and you're not PG you probably won't be with clomid.