plan A-Z?

me and my boyfriend has unprotected sex on thursday 31 of august. he didnt finish in me but he was worried so i took plan b on friday the 1st just in case jump starded my period on september 6, last month i starded august 19 finished the 24.. today we had sex condom ripped came inside me, but im on my last 2 days of me period, should plan b still work? is it necessary?