hypomenorrhea(less blood loss during periods) can be because of,
-disturbances in the prolactin
levels can affect menstrual cycle, you should not stop drugs until your doctor says.
these can be seen in some women so you need not worry, but have to take the treatment.
other causes could be
- low hemoglobin
and strain disturbing hypothalamo pituitary axis,
according to your height your weight should be 65kgs, so you try to decrease some weight which can help in success of treatment.