I am an attorney and I know a lot about this subject generally, but I am not licensed to practice law in Georgia. Do not take this as creating an attorney-client relationship. You may, however, find it helpful.
I did a quck check at websites for Georgia attorneys who practice in the area of shoplifting defense. Both of them mentioned pretrial diversion, but neither mentioned anything about an age limit.
What you absolutely must do is consult an attorney.
Do not expect judges, prosecutors, or other court staff to give you good advice. It is not their job to protect your interests. Some of them perceive an unrepresented person as an opportunity to quickly process a case. That usually means that the consequences for you would be worse than if you are represented by a lawyer. That may be what you are facing here.
If you do not have an attorney on board by the time of the next court appearance, tell the judge that you want to talk to an attorney. If you do not have the money to pay for an attorney, ask the judge to appoint one for you. Probably, the judge will then set the matter over for another day and not require you to enter a plea. If you must enter a plea at that time, then just plead “not guilty”. Make sure that you do not make any statements to the judge, prosecutor, or anyone else, in or out of court, about what happened, other than the fact that you have been charged with shoplifting.
Good luck to you.
Extensive knowledge of the subject and experience as an attorney.