What Does Bleeding Between Periods While Being Sexually Active Suggest?

my menstrual period has always been on time. It would always come the end of a month to the beginning of the new month. I got my period January 2-7, then had gotten again 17-22 but it was more dark brown to black, and i thought its okay just left over blood. Then it came again February 1-6, started off dark brown and ended dark red. Once more it came February 20-24 regular heavy blood flow. Now that is the end of march I have not receive it. Is this normal or Whats going on? ( i had sex during these months)