I've always had irregular periods. Sometimes it'll skip a month & sometimes it'll be late by a few days or weeks. I am sexually active & not on birth control. I got my period in November & it lasted for 5 days which is normal. I didn't get it in December but I had horrible cramps & very sore boobs. I got it January 3, 2013 & it lasted til the 7th. My boobs are still sore since end of December & swollen. I took a pregnancy test on Thursday morning but it was negative. My period ended 13 days ago & today is the 20th. I went to the bathroom & there was enough blood in my undies that it looked like a period & so I put in a tampon. What does this mean? Could I be pregnant? Help! <3