plan b effectiveness

i️ had unprotected sex a few hours ago and i️ seen him pull out but i️ still would like to take a plan b just to be on the safe side.. i’m really paranoid because i’m fertile right now and i️ just really can’t get pregnant.. so if you’ve ever taken a plan b, how effective was it for you? please please tell me everything.. because google really isn’t a go to place for this kind of stuff.