Am I facing possible jail time?

You definitely need to seek legal counsel before beginning these proceedings. You are entitled to a hearing and you may want to conduct such a hearing and present the evidence you mentioned. Or show it to the prosecutor and probation officer ahead of time and see if you can convince them that it wasn't intentional on your part. You face possible jail time, but that doesn't mean that is what you are going to get. Discuss the matter thoroughly with an attorney before agreeing to anything.

Your questions are best addressed to your attorney. The attorney will know your case better and know how the judge will respond. I presume that you will provide proof of completing all of the terms of your probation. If you attorney is not responding, then you should discharge them and ask for a Court Appointed attorney at the time of the Court hearing.

A violation of probation always risks jail time, but years without a further case helps. Did you ask the old lawyer why he didn't notify you? I would explore this first. Second, you will probably need another lawyer to see you through the violation.

I have to be honest, I don't know much about Shiawassee County, but most courts are pretty similar (except small towns - where they think spitting on the sidewalk is grounds for jail, or Oakland County where they think everything is grounds for jail). I would contact probation and find out what exactly it is that you didn't do to complete your probation. Since you didn't tell me what crime you were on probation for, I'll assume it was drugs or alcohol. If what you failed to complete was a class or the required hours of community service or something else that is easy to do after the fact, I would try to complete it and when you show up in court, you can explain that you were confused and didn't understand it was required but you've completed it now. In a case like that, there is a good chance that judge would close out your probation as having finished it successfully or he/she might just extend the length of your probation for an additional amount of time. If it is something where you violated - like tested positive for drugs or alcohol, you are going to have a much more difficult time. If it's something along these lines, you might want to consider an in-patient or out-patient substance abuse program before you show up in front of the judge. If I had more info, I could give you better suggestions.