Femara and positive opk

Hi ladies,

Just looking for some insight. I just started femara cd 3-7 for the first time. I had been using wondfo opks but ordered the pregmate brand this cycle. I was on cd 6 yesterday (so not even finished with the femara) and I decided to try out the opk to see how they compared to the ones I used prior. Well it was very positive. Brushed it off and decided to use another one today at around the same time. Positive again. So my question is should I trust that I am ovulating this soon even before finishing the pills? I normally have a 31-33 day cycle and if I do ovulate on my own its not until cd 17-21. Can femara cause lh to surge while taking it? Any insight is appreciated! Thanks!