Talk to Gynecologist on Delayed Periods

I had my periods on 21 of each month, this month periods didn’t come till 28, so I consulted a doctor she suggested 4 tablets of primolut n , two in morning and 2 in evening for 4 days. It’s 5 th day since I’ve finished my dose but no periods. Till when should I wait? No hormonal imbalance, no PCOs , age 24, sexually inactive (unmarried) , weight is 94 kg( gained two kg in last week)