Has anyone taken letrozole and not had ovulation until cd 26-27?

Ke

I had blood work on cd 20 and the doctor confirmed I had not ovulated during this cycle. However, last night I had a strong urge to take an ovulation test and it was nearly as dark as the control line. I know it’s negative unless it is the same or darker. But is it possible that maybe I had ovulated either yesterday or the day prior?