So I had another <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">period tracker</a> app. And that said that I was supposed to get my period on the 9th of September according to that app I'm 7 days late. This app (Glow) tell me that my period was supposed to start today the 16th and well I have not started. I did have unprotected sex on the 4th of September but he pulled out. What do you girls think might be going on?