Is Periods Occurred Two Weeks In Advance A Cause Of Worry?

Hi!!! I had my periods on the 15th Jan and lasted till the 18th jan. I had unprotected sex and took an ipill just after 2 hours of act. I consumed alcohol after 4 hours of taking pill. And 2nd feb I got my periods when I was supposed to be getting on the 15th Feb or May be a week in advance. I am wondering if I have got pregnant and also worried how could I get my periods this early.