It may be that you did a diversion or deferred prosecution for your first offense? That would mean that you were charged but the State dismissed the charges after you completed the community service and classes. Then, all that would appear on your record, and juvenile record at that, is the fact that you were charged, but it would indicate that you were never convicted.
So the State now cannot say that you have a prior conviction (unless you have other priors). They can say that you received the benefit of a deferred/diversion in the past but that's about it. You are probably going to be treated as though this is your first MIC. You are not guaranteed community service or a deferred/diversion on any criminal case. They could try to convict you. I recommend getting the police reports and doing a free consultation with a criminal defense attorney as soon as possible.
All of my statements, including answers to questions, are intended only to be educational, just like my blog at http://www.flagstaff-lawyer.com. Nothing that I post on the internet constitutes legal advice, nor does anything I post on the internet create an attorney-client relationship. If you need legal help, do not rely on what I post online, but do contact a lawyer for a free consultation. I do free consultations 24/7 at (928) 607-9928.