Confused about the period tracker???

Jay
I need some help. I'm new to this app and just recently switched over from the one I was using because my sister told me I should download it. I transferred all my data from my past periods/intimacy from my old app to glow. On the old app I had been using it since January so it was finally knowing about when I was gonna start. Well on glow after all that information was entered. It says I was supposed to start yesterday May 9th. And I didn't when I look at my old app it says I'm not supposed to start till May 18. How am I supposed to know if I'm really late? Or if there's an issue somewhere. I noticed to that the ovulation dates were different on here then they are on here. I love the app so far. Just don't know what to do about the period tracking.