Anyone else having issues with their app?

I have been tracking my period since October. I have had one irregular period and then they rest have been fine. I am not sure why the apps that I have said I was fertile the day after my period. Is that when you are to be fertile? I am so confused. It says that I ovulate 10 days after my period. From what I have read I thought t said every 12-14 days. My period comes on the exact day it says but my dates are all off. Any suggestions on what I should do? Maybe I should start fresh and delete my dates. Anyone else having these problems?