I keep track of my period on Fitbit and <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">Eve</a>. My predicted fertile days and next period are different on both apps. I’ve found Fitbit to be a bit more accurate on predicting my next cycle. Does anyone else keep track of their period on two apps and have different data? I’m confused and want to know the accuracy of these apps.