yeah man, im in a cast right now. i broke.dislocated my thumb and had to get surgery over christmas, but i have a hard cast on it, and made a makeshift cover for the rest of my thumb with my pain meds bottle, just explain that its pretty safe in the cast, and that you will be careful, and that you are taking the risk of ruining the rest of your season if you fuck up again. just act mature about it and if your parents are reasonable they will realize its your choice... or threaten to start using meth