Ovulation after stopping cerazette

So.. long one. I stopped Cerazette at the end of last month. Had a withdrawal bleed 3 days later. I stupidly counted that as start of my CD and did a 21 progesterone test (suggested by my doc) which ended up being extremely low(massive breakdown when I saw the results yesterday).

I thought I was doomed but today I had CM compatible with ovulation (still negative opk) so if I did not ovulate until now progesterone level would actually make sense. Can you ovulate without having yet had a natural period 4 weeks after stopping the pill and still get pregnant?