Ovulation when on Femara

Did anyone ovulate early on Femara? I have a 28 day cycle and normally ovulate CD12-15 (usually cd 13). Started opk’s on day 7 and it almost looked positive. Now it’s day 10 and there’s seriously hardly a test line visible. Is it possible I already ovulated? Or maybe it isn’t going to happen for at least 4 more days, hence why there is a very negative OPK? I’ve heard you ovulate on Femara 4-7 days after your last dose, so for me that would be CD11-14. First time using Femara CD 3-7. I normally get 2 days of positive opk’s and they are usually pretty dark by day 10, so I’m kind of concerned. Any help/advice would be appreciated! ❤️ thank you in advance.