I started my period on 5/28/11 and it was six days late.. When it came it was brown?

Could this be implantation bleeding? It us now red in color so is it my period Becuz I'm still bleeding? Is it possible for me to be prego since I Ov on 5/8/11 and had sex before Ov and after unprotected? Ttc please help need alot of answers