What Causes Delay In Periods After Taking Placebo Pills?

Last month my insurance got messed up and it messed up my birth control schedule. I was supposed to start a new pack on a Sunday and I didn't start the pack until the following Thursday. I took the whole pack without missing a pill. My period always comes within three days of starting the placebo pills and it's been four days and I haven't gotten it. Is this because my BC schedule got messed up and it just trying to regulate again or could I be pregnant? I had unprotected sex about 10 days ago.