Your approach is totally wrong. Birth control pills, should be taken according to the order over the pills sheet. You shouldn't not take them during menstruation/ bleeding per vagina.at age of 20, mostly you may be having Polycystic ovaries
Next Steps
the correct way of taking pills is, start them on day 5 of menstruation and continue for 21 days , then on 22nd day , menstruation starts and then continue after menstruation.
Health Tips
rather than pills, to get regular menstruation, do yoga, exercise, good diet, maintain good haemoglobin levels.