What Is The Best Method To Avoid Pregnancy?

hi........... i am 22 years old... and today i had sex with my bf but am not sure that we intercourse properly so its confusion of sperm transmitted or not? .......... on last monday i took unwanted 72 tab... Is it effective if i take it again or not? i can't understand now that i have to be taken it or not?........... my period date is almost change of every month but last period is 26th of jan to 1 feb....... Please help and suggest me ...