On birth control pill didnt miss any pills . sexual active . only had 2 day period this month and it was light . normally i have 4 days period heavy with birth control pill. what could be causing this ?

Minimal shedding: The hormones in the oral contraceptive pills generally produce a very thin layer of endometrium which minimally sheds at the time of the "period" which is actually hormonal withdrawal bleeding. That occurs so you know when to take the next month's pills. Heavy periods are not consistent with the pill and would possibly indicate a more problematic medical issue. See your GYN MD soon.