I typically ovulate on CD 13, and sometimes CD 12. This month I used CB digital advanced OPK. I got a flashing smiley for 4 days, which indicates high fertility, and then I had no more sticks to keep testing, but I'm sure my peak would've been on CD 13, and I usually ovulate within a short time, 12-14 hrs. According to my temp rise I think my O was on CD 13, and based on the fact that I was still getting positive opk past CD 11, I don't know why FF would put my O at CD 11. I tried changing the method to fertility awareness, and opk monitor, and it still keeps my O day the same. Anyone else having this issue? Any thoughts?