norethindrone

So... my ob thinks I "might " have had a chemical pregnancy in Jan...I was spotting for almost a week before my period and then had my period for about 4 days. The following month I had the spotting again for 2-3 days before me period.. so they put me on this norethindrone And said it was supposed to clear my system up... I thought whenI took the meds it was supposed to make me bleed like really heavy?? I had a nice. mostly light period.... did it not work correctly? we are ttc so I'm so confused.