Need help!!

I started my period on the 15th of last month. Most of the time I start a day or 2 before my period is suppose to come the month after. A couple weeks ago me and my husband had sex but he might have pulled out a second late but it didn't seem to be inside of me only jus around my area...yes today is the 15th but I have never started my period late its always been early...should I worry?