OPKs not working?

Sydni • 05/15/2019 👼🏼/ 🌈👶🏻 July 2020 💙

So I bought ovulation tests to see when I’m ovulating, cause I feel like this app is screwing up my times for it. And I’ve only taken two on different days aaaaand they show nothing. Not even one blue line!!! Am I doing it wrong? Am I doing it on the wrong days? Cause yesterday was my “peak” of fertility and I had sex but why am I not getting a positive on the OPKs?! I’m using Equate OPK sticks. Any help would be appreciated!!!