Period is 4 days late, still testing negative

Kalei

My period is now 4 days late, with no sign of it in site. I have been testing since the day before with Pregmate, and they are all negative. I even tried a Clear Blue Digital on the day AF was due to arrive. What is going on?

Picture is from test this morning, at 5 minute mark with FMU. I would think there would be something showing up by now if I was pregnant.