3% chance

Am I worrying for no reason?
Me & my boyfriend had sex last week, it said I only had a 3% chance of getting pregnant, but anyway we had sex without a condom, and used the pull out method, but because it was close we went and got the morning after pill, 
It's now been a week since we had to do that, and my period is a day late, am I worrying for no reason or could I be pregnant?