Hello Doctor, I Am Not Getting My Periods From Last

Hello doctor, I am not getting my periods from last 1.5 months and I have been to doctor for this she did pregnancy test and its negative, so she gave me duphaston 10 mg tablet to take 2 times for five days. I did that and after that it's been 9 days I have not getting my periods. Please help me as I want my periods as soon as possible do I need to take pills again. Also I need to get pregnant so it's very important my BMI is normal .