what is going on with me ?!

Shelby
Ok so I'm 3 days late for my period and already had two faint lines on a clear blue. And I waited to retest for a couple of days and now they are showing negatives. But still hadn't had my period and I don't feel like it's about to start. I have been off my birth control for about 3 months (which was the shot). Has anyone had this happen to them?