The reason why you don’t know what to do is that there isn’t much more to be done. It doesn’t sound as if your mother only treats you differently; it sounds like she treats you poorly. You are a young adult and the history of your relationship with your mother is clear, and you have been pulled into the role of staying home, caring for your sister, and following your mother’s wishes. It is time for you to plan more directly for your independence. Your individuation from your mom is important. Developing yourself away from your family as you move forward is essential as it doesn’t sound as if you can change the dynamics within the house.
Becoming an independent adult with the capacity to meet your own financial, intellectual, and emotional needs is an important goal for you to have. You are not going to solve this with your mother alone, and from your explanation, there isn’t another family support in the home.
This means having a family therapist meet with you and your mother would be the best therapeutic road to go down, but if your mother refuses I would highly recommend getting a counselor at the community college, or an individual therapist to begin helping you develop a plan to move on. There isn’t much support emotionally you can get from your mother, and it doesn’t sound like your sister is in a position to be there for you either. This leaves you with the task of finding support from outside your family to sustain your own growth and development. Writing to us here is a good start. I would encourage you to find ways to continue getting support for yourself as you work toward and build an independent life.