Grrr...I hate it when people actually make sense...
Have you tried a different approach with your sister, maybe trying to be a friend to her. You two both seem like complete opposites.
You graduated from college, don't think she did
You have a good relationship with your folks, sounds like her's is questionable.
You have your own apartment and your own life, she's still living at home, being supported by her parents.
You have your act together, she's still trying to find hers.
Instead of trying to fix what's broken in her, and point out what's wrong with her, just be a friend to her, sounds like she could use one, especially one that would be such a good role model for her.