Provera Question

Sari • Married 7.5 years. Just had our first child, a baby girl on 4/20/16! 💗
For those of you that have either used or know about using Provera, do you know how late AF has to be to have your doc prescribe it? I'm on CD 34. No sign/symptoms of AF anywhere and neg HPT. I don't really know how late AF is since I just went off BC two months ago. She showed her ugly face on CD 31 last month. 
Also, can you ovulate regularly after taking it? Is there a way to test to make sure other than OPKs?
Any info would be greatly appreciated! Thank you!