How mature do you act now? Are you another teen prone to "stupid kid tricks?" Or do you do well in school, take good care of yourself, your clothes, your room, etc.? Pitch in on household chores (you're part of the household, everybody helps out!)? Do you make reasonably good decisions, or foul up time & again? By 15, you should be able to pretty much take good care of yourself & your possessions, be competent at laundry & ironing, cleaning your room, keeping a positive attitude, thinking things through instead of being irresponsible or "just plain impetuous & stupid."
Got all those ducks in a row? Then it is time to talk to your parents about expanding your horizons, expanding your boundaries, as so far you can manage yourself well. Next step is time to discuss college financial planning - in a general way to start! - with parents. Don't whine. Don't start off with South Carolina (you may find a better school!). Build your discussions step-by-step.