Your Opinion Please. Implantation bleeding? ?

I have been taking Alesse birthcontrol for 7 months now, i take it at the same time everyday and havent missed a pill, i took one late about 4 months ago but thats it. Me and my boyfriend havent used condoms for about 4 motnhs now (he pulls out before ejaculation) but on thursday night we used a condom (ribbed) and a new kind of lubricant but we had pretty rough . friday night i noticed a brownish pink discharge when i wiped and it is now tuesday and i still have it on and off im due to get my period on friday as i always do on the day of my forth green pill but im not sure what this discharge is all i can find is that it could be implantion bleeding. Please let me know what it could be other then pregnancy( i thought birthcontrol stopped ovualtion what are the chances of me being pregnant after taking it for 7 months)?