Replying to Breaking in Full Tilt Classics

hey guys, recently bought some Ft classics, i have size 10.5 shoe and i got 28.5 boots. ive never had new boots before, so idk what its like, for the first few runs felt good, but then i couldnt figure out the tightness i liked, when it was tight it hurt, and when it was in between my heel would slide up when i landed switch. and i would get toebang.. please help. im 15 so my feet will grow if there to big, my foot touches the end and they fit perfect other wise..