Missed period concern. Of the tablets.

I experience a lot pain periods so for that I went a doctor for treatment. She gave me these medicines. Before this My period was also regular... I don't have pcod/pcos.... My last period was on April 30 I started taking dronis 30 from 19th may .....And next period was supposed to be on 28th may bt i missed it. They said in the 7 days gap of the dronis tablet i will get it. Bt till now I didn't get.  I had intercouse on 25th may also . Bt it was protected. So why I am experiencing a delay in the periods?is there any chance of conceive or because of the tablets... And when will I get my periods.. I am worried about it. Last period :30 April Next periods :28th may Dronis start -19th may Dronis tablet end -8th june Still I dint get my periods . What should I do. I did pregnancy kit test ..it's negative.