First Round of Femara...When Did You O???

Callie • 👶🎀 8.18.18. 👶🎀 3.16.20.
Hey guys! I'm on my first round of Letrozole, 2.5 mg, CD 3-7. I started using OPKS on CD 11, like my doctor advised, but today is CD 13, and the test line is still barely visible... The doctor estimated I would O about 7 days after finishing my last dose (CD 14), but that's not looking accurate... am I out or do I still have a fighting chance?