A lot of things factor into sentencing, including the conviction charge. You may, for example, be able to plea bargain this down to a misdemeanor. If the court believes you're mentally ill and are getting treatment, that may influence the sentence as well. (But that implicitly involves telling the court that you've been getting away with a lot of shoplifting, so be careful how you approach that.)

The best way to find out what lawyers in your community charge to defend people against felony shoplifting charges is to call them and ask.