Morning after pill, period 2 weeks early?

Hi, don't know if anyone can help... Had an incident with a condom breaking so took the morning after pill within 12 hours of having inter course. Within 3 days I had what seemed like a period for around 4 days (usually my periods are 5 days long) and this started really light and heavy on last day. But problem is that if this was my period it was 2 weeks early! I was meant to start my actual period 2 days ago so now I'm worried I could be pregnant... Anyone been in a similar situation? What shall I do?