12 days after my period I have light pink then brown discharge

I have always had regular periods thatstarted at the beginning of the month and lasted for 7 days. But the month before last it started 10 days late and was heavy the first day then was hardly anything for the next 3 days then it went away. So it only lasted 4 days then last month I started on the 2nd which was refirst normal but again only last 4 days. Then this month I started on the 8th which was really heavy and hadinsane cramps but the next day was rather light and on the 3rd day it was gone and came back the 4th day and stayed till about the morning of the next day and went away My husband and I had sex on the night of the last day of my period and 12 days later I experienced light pink discharge for about a day and a half, and on the other half of the second day I had dark brown discharge that lasted for the rest of the day. I'm nauseas, headache, tired, moody, and sore breast. Can I be prego :)