Suggest Medications To Induce Period

Iam 23 years old, our marriage has been arranged on Sep 8th. My period falls on 19th of every month and it will be normally for 3 days. Because of my fiance we had on unprotected intercourse on 22-4-2011(4th day of my period). Now Iam very much worried because it has crossed 6 days still Iam not getting my period. I feel the pain in my stomach but still period is not coming. My mother started questioning me. Kindly I request you to advice me and also pls give the name of the tablet which helps me to start the period.