The guys are correct...if that was an extortion scam, you would have heard from the girl's police friend by now.
To be safer still & help you to relax, best option is to change hotel....but make sure to tell the hotel receptionist that you have to go home early due to some....well, make up some cock-and-bull-story or no need to give them reason.
The fact that her two friends stayed down at the lobby mean that was a genuine "quickie" for some fast money and not a scam.
Haiyah...I too have very similar experiences with yours (twice...one 16 and the other 17) , but I screwed them anywhere