Why the variations?

ha

Why do some women test negative before their periods and hard positive the day of? Others positive a week before and some even have to wait a few days AFTER to get that elusive line!??

When <a href="https://play.google.com/store/apps/details?id=com.glow.android">tracking ovulation</a> there is no way you can be THAT off is there?

I don’t understand 🤣