Hello
Welcome and thanks for asking
Birth control pills can cause irregular periods sometimes , if missed there can be chances of pregnancy and heavy bleeding can be the sign of miscarriage
You can do
pregnancy test at home with kit
If doubtful get one ultrasound done
Beta hcG test will confirm
Next Steps
do not forget to take pills for two consecutive days , if missed for one day you can take two tablets next day
Health Tips
take iron supplements
get HB test done
best wishes