Hi Im 32yrs. My Last Period Was January 12th 2016

hi im 32yrs. my last period was January 12th 2016 and it was 12 days long for the first time my periods are always regular 7 days long I did go to the doctor once my period in January lasted 12 days and all test results came back normal even my pelvic exam so once I got off that long period I had sex February 8 and the 12th unprotected and I didn't get a period this month February do you think cause I had a long period in January or because I was sexual active in february