I was on depo birth control for almost a year and i got off a few months ago . i had my period for like 2 and a half weeks straight then it stopped . then came back the 13th of feb. and ended the 18th . i should have ovulated on the 27th of feb and i had unprotected sex on the 25th of feb . march 4th and 6th . i should start my next period on the 12th of march and i started having brown spotting on the 8th what does this mean ?