What do y'all think??

Chelsey • C.Wooten
I randomly did this opk this evening, strongest results I've had since I started these. But just 2 days ago it showed me a blank circle.. Today it showed me peak fertility?? Also exactly a week ago it showed peak fertility.. I'm having period like pains and mostly pain on right side. AF got off track so could either be due now or in another week 1/2. Why is this so strong when there was nothing 2 days ago? Can these detect HCG also?