Like the others, I agree that your expectations are healthy and reasonable.
Why do you see yourself as "mean and bitter"? You are sacrificing your dreams and desires and needs, and your family is taking advantage of that. Those are the actions of someone who is generous to a fault - the fault being that you are giving to an unhealthy level and denying your own needs.

I agree with s4ndm4n2006 that paying university fees is a parents' responsibility, and your parent is still alive. Maybe paying your sister's uni fees will help motivate her.
I can understand if you feel bitter, but the things you want and expect are very reasonable and healthy.