Period delayed?

I've been on birth control for about two years (the pill). My period is always on time and lines up with my calender on this app. I take my pill at the same time every day and I never miss a pill. My period was suppose to start three days ago, but nothing so far. I've had mild cramping for the past week, but my period isn't in sight. I am sexually active with my boyfriend of 4 years. We always use condoms as a backup with my birth control so we're double protected. I don't think there is a possibility of pregnancy, but I took a test anyways. It was a BFN. Has anyone else experienced something like this? I don't really have any period-like symptoms going on other than excessive tiredness. I'd love to hear your two cents on this. Thanks!