Welcome to HCM.
UNWANTED 72 contains high dose progesterone
It decreases chances of getting pregnant.IT is an emergency contraception
However it can cause breakthrough bleeding
and may cause irregularity of menstrual cycle in few cases.
You should not worry the pill does not have any long term effects your cycles will get regularized in few weeks.
Just take care while having sex with your boyfriend and dont make habit of taking UNWANTED 72 each time.
Just relax dont worry about the pill.