Ovulation days wrong!!

For everyone following this app that is ttc I highly suggest you buy some cheap ovulation test and take them the days it says you are supposed to ovulate! I have been going by this app and ttc for 10 months. After I went to the doc and had my progesterone levels checked she suggested I buy ovulation test... I took them for 5 days and my fertile days were actually a week later than the 2 apps I follow told me they were!