When did you ovulate on Clomid?

Diane
I have PCOS, and started my first round of clomid this cycle. I used OPKs twice a day from cycle day 10-31. I finally got a positive on day 31. Is it normal to ovulate so late while on clomid? Is there any way to find out if I really ovulated? I'm now on CD 33, and no sign of AF (knock on wood). My cycles are usually 29-30 days long. When did you ovulate on clomid?