Of course you need an attorney. Speak with your parents about this issue and have them help you find an attorney competent in juvenile law.
I agree with the previous answer and NEVER rely on an officer saying he will testify in Court for you to get the charges dropped. I've heard that a million times and its usually a lie. Probably designed to get you to make further admissions they can use against you.
You should definitely talk to an experienced criminal defense lawyer. These are serious misdemeanors that could affect you down the line, if you are convicted. Depending on the county, a lawyer might even be able to get you a deal that would involve a dismissal of the charges, possibly without you even appearing in court.
You should certainly hire an attorney in Iredell County to help you with this situation. You want to avoid a conviction if possible because this could negatively effect your ability to get into school or get a job. I would be happy to refer an attorney in your area if you are interested.