I’m so confused !

So I had my period last month Sep.23-27 And I had sex about a week ago I had taken a plan b on October 5th it’s now the 12! And I got my period again. Is it true it can speed up your cycle ? Because I was suppose to get my period the 24-29 of this month . Because I know it’s not spotting ! I’m literally bleeding ! Can anyone explain to me ? Has this ever happened to anyone else. I’ve taken a plan be before but my period didn’t come that quick it came only a few days earlier!