Why Am I Not Having Periods After Stopping Primolut N?

i was on religious plgramage ... and was taking primolut n .. for 8 days but at different timings ... now its been 4 days i have stoooped but no periods ... the sister who was also taking the same medicine had periods yerstaday .... m polysistic ,.. had 2 miscarriages and desperatly looking forward for the baby