How accurate is this app? Because as of right now I am 1 day late no sign of AF. But im too nervous to take a test. My husband and I did BD 3 days before 6 days before it says my fertile window and the day after i was suppose to ovulate. Like the last day of my window. My husband and I havent really been trying because we kinda gave up because we have been trying for a few months. We have a 5 year old and it took us 3 months to conceive him. So i was wondering how accurate everyones window really is.