Period last dec. 14-17. had breakthrough bleeding dec. 25-31 then stopped pills. around when should my next period be? when to test if pregnant?

Hard to guess: After stopping pills in the middle of a birth control pill pack, there may be some withdrawal bleeding. It is hard to guess when the next normal period will be, as that might depend on a woman ovulating within 2-3 weeks (but not every woman ovulates within 2-3 weeks after stopping the pills). So, if no real menstrual period occurs about 5 weeks after this withdrawal bleeding, can do a preg. test.