I M Not Having My Periods Since 4 Months As

I m not having my periods since 4 months as I have taken pills after the sex but after dat I had my periods.. but now it had stopped for 4 months. My pregnancy result is negative and as per doctor's consultant I have taken deviry 10 mg for 1 week. It's been two days I have not taken the tablets but my period is still not coming. Please help what should I do?