Am having unprotected sex for the past 3 weeks.but now am having vaginal bleeding and my period is due until the end of the month.

Not necessarily PG: Having non-menstrual vaginal bleeding does not make me more concerned that you are pregnant. In fact, bleeding (unless it is a miscarriage) is LESS likely during pregnancy. Other things--hormonal change, infection, trauma--are more likely causes of bleeding. Unless the bleeding is severe, ok to wait until expected period starts. Of course, do pregnancy test if late! See doc if bleeding persists.