Period help (TMI)

Susie
I have always had a regular period, always occurring on the 2nd of every month and lasting about 3-4 days, with a moderate flow. Suddenly the last two months it has been a little over a week late and when it finally comes it's just a little bit of pinkish brown spotting?? Help?? I have had unprotected sex and have never been on birth control, could this be related?