For you haven't got your periods and that your pregnancy
test came negative leaves many possibilities. You haven't ovulated in this cycle, your ovulation got delayed and by that delayed ovulation you did get pregnant or simply you didn't. The trick of duphaston
is that if you aren't pregnant, on stopping the drug, you will get a withdrawal bleeding like menses. If you are by any chance pregnant, you won't get this bleed and in that case it will act as a sort of pregnancy support. If you don't get periods in stipulated time and even then your pregnancy test come negative, it warrant further investigation. I didn't get the other drug as you have used the trade name and I am not familiar with it.