Well, I had unprotected sex on August 18th and took plan B the next day on the 19th. My period started on 20th (very light) and lasted until the 28th. Normally my cycle is every 17 days. My period tracker says my period should have started on the 14th of September and today is the 19th. I took a pregnancy test early afternoon and it said not pregnant. I've taken plan B before and it's never delayed my period this long. I have been having menstrual cramps so I'm hoping my period will start soon. Is there any possibility that I could be pregnant? Or did the plan B delay my period more than usual?