How do you get a 2/3 day period while you're on the period? I'm 12 and I'm 2 days into my period?

Hi, I'm 12 and I'm 2 days into my period but I don't want it to last a long time because I'm going to a hotel with my mum, dad and my friend but we're meant to be going swimming and going hiking and all these amazing things that I won't be able to because, when I'm on my period I get REALLY bad cramps especially when I'm moving about, my mum already knows about this and I've told her and she said we might have to cancel it, but it's 4 days away (We're going on Saturday) and if my period leaks onto the bed in the hotel and my friend will be there and I'll be so embarrassed.. Please can somebody help? And also I won't use tampons.