I believe that people can turn their lives around, and I'm certainly not the same person that I was at 18.
Having said that, however, I'm a little puzzled by a few things ...
1) You "guess" you were convicted? You don't know? This kinda seems like a big deal, not a minor detail that might have slipped your mind, KWIM? Have you applied for & gotten jobs since that time?
2) Did your school not run a criminal history check, or require you to obtain one, or at least advise on their application that there are circumstances that preclude licensure as a nurse in your state?
3) As soon as you were told about the fingerprint check, did it not occur to you that this would be a problem? You waited for the check to come back and were suprised at the results?
Unfortunately, unless your record is somehow inaccurate, I sincerely doubt that an exception will be made for you.
My school's application quotes the regulations from the state board of nursing - unless 10 years has elapsed since a felony conviction or any conviction involving drugs or alcohol, it's very unlikely that a person with any of those convictions can be licensed in PA. Individual hospitals used as clinical sites may have additional requirements as well, and nursing programs
have no control over those.