AF is 3-6 days late. (I use two different apps and they always give me different prediction dates but always in the same week)

I've had negative tests with Fmu for the last 3 days.

Last cycle, I had 1 day of medium flow and 2 days of spotting afterward.

Any thoughts as to what could be going on???? I know stress can mess up your cycle and such but I don't have a whole lot of stress????