Talk to Gynecologist on Periods

Before pregannacy i always have a cycle of 28 days of mensis but after my c section i got periods after 2 to 3 months and now its going to be complete 6 months of my c section on 13 th july . my last Menstural date is 9th May and strip test is negative even after dr prescribed me Primolut N for 5 days My periods is still not come .i am very worried .doctoe also did an strip test plus ultrasound after missed periods of 12 days