Is Brown Vaginal Discharge While On Mercilon An Indication Of Pregnancy?

HI. I ve been on contraception since January this year. First started with Yazmin but it didn t work for me well. So now I changed it to Mercilon and it s been a second month of me taking it. I wanted to skip my period because I got a lot of revision right now and my period pains are really not helpful so I skipped my period and now I ve been getting a brown discharge and it would come at certain times of the day and disappear when I get up to stuff with my bf. Last night we had unprotected sex (no condom). Is there a chance that I might get pregnant since I ve been getting this discharge? I.E Can discharge mean that I m unprotected?