This app is amazing! Even with irregular periods the app helped me find my correct ovulation and fertile days. The more info you input into your daily "diary" the more accurate the app will be. Just this morning the app told me there was a change in my ovulation date. I accepted it and allowed the app to change my calendar. My curiosity set in and I purchased an ovulation test. The app was right!!!!! Thankfully Ive been having unprotected sex the past 9 days (since I was extremely frisky lately during my now fertile window). Im keeping my fingers crossed :)