I have taken the morning after pill and the next week the planb, 2 days after the plan b i when onto the 3month injection, my period never came when it was suppose to which was a few days after the first morning after pill but it did eventually come.

About Plan B...: Plan B (or other morning-after pills) can alter the menstrual-type bleeding for the cycle in which Plan B was taken, and sometimes the next cycle too. One should check a home pregnancy test about 3 weeks after sex because Plan B works most of the time, but not all the time. If normal, regular periods have returned, pregnancy testing is not needed.