at seventeen, south carolina treats criminal offenders as if they were adults, so your age has little to do with it, although you qualify for a youthful offender status.
As to the misdemeanor issue, the value of the items taken determine whether it is a misdemeanor or felony. If the value is less than $1000.00 it is a misdemeanor. If greater then a felony. Key is to attack the value. obtain the store's purchase records of the item if it is close to a thousand and argue their wholesale acquisition cost versus their retail mark-up.
Also, this is the type of case that will frequently be remanded to magistrates court as a misdemeanor just to give a kid a break and clear up the court docket. You need a lawyer to negotiate this for you, or give you a good trial defense if deal-making does not work.