Y every time i have sex with my boyfriend i spot?

Infection?: Infection or some sort of vaginal, cervical or uterine abnormality is most common cause of post-coital (after sex) bleeding. Check out http://womenshealth.About.Com/cs/menstruation/a/bleedaftersex.Htm & http://www.Medscape.Com/viewarticle/412468. Then go see your family doc for evaluation. And use protection unless you want to get pregnant.