Hi You have not mentioned whether you had regular periods before pregnancy. Periods usually return in four to eight weeks time after miscarriage. But note that the time it takes depends on how regular your periods were before pregnancy. It is nice to know that the ultrasound shows a dominant follicle. Based on this i presume you should get periods in three weeks time. If I were your doctor I would suggest that we wait for three weeks to see whether periods occur. If there is no period after three weeks I would give medicines for period to occur (after checking for pregnancy test). After that period cycles usually reestablish like they were before pregnancy. If not I would do further investigations and evaluation.