I Have Been On Birth Control For About A Year.

I have been on birth control for about a year. I was off of my birth control for a week due to prescription errors but started it a week later. I was on it a week before having unprotected sex and he did pull out. My period was scheduled for last week but according to my birth control, my period is supposed to start this week. I have been cramping as I usually do before a period but it's been a week. Should I be worried about being pregnant or did I just change my period schedule to this coming week?