Am I not doing enough? I feel like nothing I do is appreciated.

Lately, I've been feeling really overwhelmed. I do a lot for my sister; I do all the house chores, and I even delay my own schoolwork so that I make sure the housework is finished. It still feels like what I do is not enough. Whenever I try to prioritize something important, like going to the library to participate in a group project, it becomes a problem because I have to wait for a deliveryman. The next thing she tries to find issues in everything I do. I get told I am no longer cooperating, even when I'm honestly trying my best.

It's making me question myself a lot. I don't know if I am doing something wrong. I know she is the reason why I attend school, but being made to feel guilty for my own responsibilities is becoming heavy for me. I just want to understand how to deal with this, because right now it's really getting to me.