Hi Dr I Had Unprotected Sex With My Bf On

Hi dr
I had unprotected sex with my bf on 13/03/15 n had oral contraceptive pill on very next day. Again we had sex but protected (with condom) on 21/03/15. My period usually comes on 4th/6th day of every month. But I didn't had my periods in this month(April). Even I took pregnancy(preganews) test on 10/04/15 but it came to be negative. But m worried a lot as m not experiencing my periods. Plz dr suggest me the best I can do to get rid of this missing period...its worrying me a lot. What medications should be taken for having periods back to normal.....plz help.