Random question but confused

Hi everyone!

Can someone please help, I have two apps as I am ttc for first time and want to track my cycle but my glow app is predicted for my monthly to begin today which if it is then it’s late and I have no spotting or anything to suggest it’s going to start apart from bad cramps, boobs sore and sickness that started over 10 days ago. However I have another app called Flo which has predicted my monthly to start in 3 days but I don’t know what to go off. Glow has been correct for the other months though.

Lauren