Crimes are grouped into three categories: summary, misdemeanor and felony. Misdemeanors have three tiers: 1st, 2nd and 3rd degree. A 1st degree misdemeanor has a maximum punishment of up to 5 years of incarceration and a fine. Assuming your information to be correct, you will be eligible for a deferred adjudication program for first time offenders called Accellerated Rehabilitative Disposition (ARD). If you complete ARD successfully, your record will be expunged.
You should hire an attorney right away.
There are three degrees of Pennsylvania, first degree being the most serious. The maximum sentence you could receive for an Me is 2 1/2 - 5 years incarceration. However, based on your account and assuming you have no record, you should be eligible for the ARD program. You will be placed on a period of probation and once you successfully completed it, you can move to have your record expunged.
You may very well be eligible for ARD but do not assume that you are. Some counties have specific requirements about what is and is not an ARD eligible crime. I have seen folks denied on theft above a certain dollar amount as well as theft from a School so make sure to consult with an attorney in your area before making any decisions.