You can bleed while on birth control. It is called break thru bleeding.
Your hormones are probably in an awful state since you aren't taking your birth control pills consistently at all. And, not taking your birth control correctly and as prescribed, can lead to pregnancy.
You may want to take a pregnancy test. When it hopefully comes back negative, you need to re-evaluate your birth control. Maybe you need something that is less restrictive and requires timing and consistency. Maybe you need to find something that is more spur of the moment.
Whenever you miss a pill, you need to use a back up birth control method (condoms).