Apps are great for helping us track and predict but they are always a guess as they don't measure hormones. You've had a hormone shift by discontinuing birth control. So, you are possibly recalibrating for what your normal, non manipulated cycle is like. So, give it some time. But the app will start to catch what your normal cycle is like off birth control, it will then tell you what it thinks your most fertile days are and that is a great guess. :>) Happy baby making!