It can be confusing sometimes to figure this stuff out. Apps are good for tracking and can predict only based on data which isn't always how our body works. Our hormones can switch up and we have an off cycle. Reasons for why a woman is late include stress, changes in routine, illness, weight gain or loss. Pregnancy tests are accurate about 2.5 weeks after we've had sex. So, it seems like it has been long enough. And pregnancy tests when taken at the right time and read correctly are very accurate. I am guessing your period is on the way, hon. Take a test in a week from now if you haven't gotten your period.