What are my options as a juvenile to get this off my record or at least reduced?

I am fifteen years old. I was caught shoplifting on 12/31/16. I took over $100 in merchandise but it was less than $300 dollars. This was the first time I have ever been caught shoplifting and the second time that I have ever done it, with the first time being 12/28/16 and Loss Prevention knew of this but they didn't catch me that day. They told the police this but I believe that the police only write down the value of what I stole for 12/31/16. I didn't steal any actual merchandise only store testers which I (apparently wrongly so) thought were of no retail value. Loss Prevention told me that this will not go on my permanent record but they called the police so I want to know if what they told me was true. They had me sign a paper saying that I would never return to the store and that I know that I committed the crime. They had me write down what I stole and sign papers acknowledging that I did. I think this count as a confession, right? The police took down my information and description and the store’s Loss Prevention gave my mom a civil fine for $200.