Leterozole cycle 1 - totaly confused

Hi i am on leterozole cycle 1- 2.5mg day 3-7. I have pcos

I had an ultrasound day 12 and the gyno said i will be ovulating soon within a day or too. 1 follicle on left was large.

Its been 4 days after that and my ovulation strips are only faint lines still… i was expecting them to be darker but it seems to be fading more and more each day.

Can anyone rxplain what might be happening? Is the leterozole failing in making me ovulate? Gyno didn’t tell me any size or anything about the follicle so not sure