Can i still ovulate or get pregnant after/during breakthrough bleeding? im bleeding again when my period ended 12 days ago?

Pregnancy is know to have occurred from sex on any and all days of the cycle. What you are experiencing is not uncommon due to normal fall in estrogen level during mid-cycle.

For your information, each menstrual cycle begins with the onset of menstruaton, no matter hw long the period lasts. "Breakthrough" bleeding suggests that you are in need of a change in BCP rather than in need of added contraception.