Are my parents being unfair?

Im 19 my sister is 21. We both still live in my parent’s house. Meaning we each have a part to do within the house. My sister and I share a bathroom she cleaned the bathroom ONCE this whole year. Her and her boyfriend uses the bathroom in the basement on weekends and make it disgusting. I cleaned it once for them she didn’t even say thank you. I’ve asked her many times to help but she doesn’t. I told my mom the situation and see is not doing anything about it. I work full time but I still come home and clean the WHOLE house and more. My sister can’t even clean the bathroom. My mom is saying I’m the rude one for saying she doesn’t do anything. What should I do?

I can’t move out I wish
Are my parents being unfair?
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