Maybe try the longer, overnight pads. If your mom thinks it's ok for you to wear tampons, then wear tampons and pads at the same time, but do be sure to change the tampon as often as recommended on the box.
this happens of girls your age and it actually does bleed more at night or whilst your asleep I would suggest just changing your pads as often as possible and also maybe wear two instead of one and see if that helps I actually found a pad that is bigger than the normal pads they are for incompitence and they actually work great for periods.
if its really bad you can go to the doctors and they might give you medication/ birth control that will help, there are pads out thee that are for heavy periods.