Late and light period

Patient: I just came off of Yaz birth control in Sept and had one regular period after that. My last period was on October 13, 2011. I have a 30 day cycle usually, so i was due on november 12th. I had sex basically everyday from October 17th- Nov 11th, since i didn’t know when i would ovulate. I didn’t have any sign of period except for the fact that I had cramps from Oct 28th on and off until November 8th. On November 16th i started to have some brownish bleeding which was light and only when i wipe. I have had the bleeding now for just over 2 days but it is still very light, some red blood but mostly brown. I took a pregnancy test on Nov 15th since my period was “late” and it was negative.Could this new bleeding be implantation? or could I still be pregnant? or what is all this? I’m a healthy 26year old woman. I am not stressed and havn’et gained or lost any weight recently…i’m also not obsessing about getting pregnant, but now i just wanna know what’s going on…

Doctor: