i had that happen to me a while back and i didnt bleed when my period was supposed to come. so dont be surprised if your period doesnt come when it is supposed to because your body might be acting as if this is your period now!
what BCP are you on? it might be too low for you...have you been hanging out with girfriends a lot recently? for me...i was on ortho-low and my best friend and i were hanging out ALOT together, as our husbands were in the navy and on deployment...well her and i were on different cycles, but all of a sudden my period started to regulate itself to her cycle..i called my doctor and they were able to prescribe me a higher dose of BCP....which helped. when women are together a lot or for an extended period of time, their cycles tend to regulate so that they are on the same cycle...weird i know, but it happens...