Im not 100% sure... what i do know is that cm and ov pain can come AFTER ov as well..
I think if you've got a positive opk and you very busy on those days you should be fine..as the test obviously dected a hormone surge, so you could've ov the 17th and still have residual effects of that on cd 20.
thats what i think, anyway
Happy 2ww wait, babe, and hope you get a bfp this month!!!
xxx