22f.on 2 bc pills to stop period due to endo. nothing for 2 years, suddenly im bleeding. no intercourse for 3 months, no std, no missed doses. normal?

Probably DUB: Dysfunctional Uterine Bleeding (DUB) is your most likely cause. Check the 'net and see your OB to discuss management.

Breakthrough bleed: Breakthrough bleeding (bleeding at the wrong time) is very common on birth control. It happens in about 1/3 of users. Its no big deal and usually self corrects over time. If you are not satisfied or it continues to happen then consider using a different birth control method. It is a common side effect and does not mean something is wrong or that the pill is not working.