Why Am I Missing Out On My Periods?

Hi doctor, I am under treatment for PCOS.Last december I did lap ovarian drilling(operation).then doctor advised me to take regular Metformin 1 gm ,loprin 75 etc.after period day 3- 7 Adova tabs then dufaston day 16 - 25.my last period was on 22 jan and last dufaston dose on 15 feb.but till now i have not any period so today on 24 feb i checked by pregnency kit & found negative. So what can i do? and Is it any chance to conceive?