Other counsel are correct. You should conduct yourself in an exemplary manner for at least 7-8 years, and then consider an application to the PA Board of Pardons for a governor's pardon. Legislation is pending to allow expungment of M3 offenses, but until it is enacted into law, a pardon is the only viable option to clean your record.
Unfortunately your only options are to find an employer or career for whom the conviction is not an issue. You are not eligible for expungment and in my opinion it is way to soon to even think about a pardon.
This information does not create an attorney /client relationship and should not be use or relied upon to make any decision in your case. Only consultation with your own attorney can provide you with the advice you need for your case.
Unfortunately, I speak with many people who have a similar issue. Currently, I believe the state legislature is considering whether to allow expungements for misdemeanors of the third degree. However, as of now, you should wait seven or more years and apply for a pardon from the PA Board of Pardons. As to your career situation, check with your local employment office or speak with someone familiar with helping people find jobs. Many employers work with probation and parole offices to help people in similar situations.
This answer is based upon the knowledge of its writer and in no way creates an attorney-client relationship.