My boyfriend he ejaculuated on the top of my vagina by the clitoris on the 21&my period is on the 27, i took the plan b pill, will i get pregnant?

Always possible: It does not appear that you were in your most fertile time (if you are normally regular) and you say you also took plan B (I assume correctly) so it is pretty unlikely that you are pregnant; however, I never say never... If you are sexually active (especially if you aren't using a reliable form of birth control correctly ALL of the time) then you always have a risk of pregnancy.