I use <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">Eve</a> and Glow for period tracking. They predicted my fertile period a week apart from each other. CD1 for me was Feb. 28 and Glow predicted my fertile period as Mar 8-13 and <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">Eve</a> predicted it for Mar 15-20. I loosely monitored my CM and think I ovulated around Mar 14. Around the 21st I began feeling constant nausea, loss of appetite, cramping, swollen breasts, extreme exhaustion, bloating, thirstiness, constipation, and dizziness. Technically my TWW would have been over when my period was predicted on Mar 29. I tested on the 23 which was negative and I felt that was too early to test. My period came early on Mar 25. It lasted two days and was so light it took 6 hours to fill up a regular tampon. (Also I've been told having a period doesn't actually mean anything, my mom had several before she was sure she was pregnant with me). But is it possible to actually be pregnant?