Sex on the last 2 day of period,unprotected.took planb pills 5 days later, 9days after planb got heavy bleeding again. i miss a period , 3 neg tests.

About Plan B...: Plan B can alter the menstrual bleeding for the cycle in which Plan B was taken, and sometimes the next cycle too. One should be sure to check a home pregnancy test about 3 weeks after sex, because Plan B works most of the time, but not all the time. One should be sure to have a reliable type of ongoing birth control, the PlanA, in order to never need the PlanB again.