Ovulation confusion

daneka

I have 3 different <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">period apps</a> glow, ovia an flo and there all telling me different fertile windows I've entered the same details on all apps

Ovia is saying my fertile window starts on the 10th

Flo makes no sense according to the calendar I have 11 fertile days starting today

glow is saying my fertile window starts tomorrow