Can't delete projected periods

I mainly use the app to track my extremely irregular cycle so I know what to tell my healthcare providers. But glow has been creating "predictions" that I cannot delete. My last period was in January, and the app have since decided I have a 40 day cycle and created period dates in subsequent months that I cannot delete--I can select them and hit "delete" but they either reappear immediately or I get a message saying "you cannot delete your most recent period." This is troubling since I'm starting to forget when my cycles actually have occurred vs what the calendar on the app claims. What should I do?