What Causes Absence Of Menstruation Post Intake Of Duphaston Tablet?

Hi, I have irregular periods and I am trying to conceive my doc suggested me to take duphaston twice daily from day 14 of my period till day 28. Today is my day 30 and still no sign of period. This is my first time of dydrogesterone so when can I expect for periods or if I hv conceived can this be checked immidiately??