If I understand correctly, your case and your plea and sentence were in New York, but you subsequently moved to Pennsylvania. This may be part of your problem.
Each state has different requirements for Megan's Law and each state's Megan's Law Statute is unique. As a result, the information you were given may have been correct so long as you were residing in New York, but may not have considered how the offense would be treated by another state. In other words, what you pled guilty to in New York may only be a ten year registration requirement, but that same offense (or type of offense) may be a life-time registration in Pennsylvania and Pennsylvania will treat it as such.
megan's law is complicated, too much so to address with email. It sounds to me like your attorney avoided the SVP (sexually violent predator) component of the statute for you which requires lifetime reporting in addition to jail. If you are guilty or didn't want to take the risk of a teary eyed little girl testifying in front of a jury, you should consider yourself lucky. If you are truly innocent, perhaps you should hire an attorney who has an excellent record with appeals. Somewhere in your court papers or on the record, your megan's law requirements should have been explained to you. In my county, they are agreed to in writing, signed by the defendant and made part of the record. Perhaps this was not done, but it is unlikely. It sounds like you are confused as to everything that happened. Perhaps you should review all of your court papers in the County courthouse or order the transcripts of your plea and sentencing to see what you did and did not agree to on the record. This may cost you some time and a few hundred dollars, instead of paying an attorney as sizeable retainer to sift through all of this information for you.
William R. Pelger, Attorney Munhall, Pennsylvania 412-461-1900