Irregular Period

Is it possible for periods to become irregular again?
Before I started birth control a few years ago my periods were so irregular I never knew when they were coming. I was on the pill for a 4 or so years, and have been off of it for almost 2 months (my prescription ran out, we just got married and haven't been able to get a doctors appointment). My period is 2 days late now and just wondering if it's possible to become irregular now. I got my last period ontime but not this one. I just took two pregnancy tests and both were negative.