Took morning after pill on feb 1. got withdrawal bleeding on the 12th. had light menstrual bleeding a week after. took 4 pts, negative but no period?

You're fine: It sounds as if you are definitely not pregnant. There can be other reasons that you haven't had a menstrual cycle, but it sounds like not related to pregnancy. Other reasons might include, #1 hormone imbalance, thyroid issues, weight (thin/heavy). If this is first time, i recommend wait it out. If happens more often, see a doctor, consider cycle control with birth control pills.