YTA. Not even YWBTA. Your sense of entitlement shakes me to the very core. WOW. Not only are you ungrateful for your sisters sacrifices, but you are a complete leech. You expect her to pay you for babysitting but you don’t care to pitch in more for house expenses. On top of this, how do you feel like you deserve to be paid when all your living costs are covered, including education. Is that not enough? Your sister seems like a wonderful woman and I’m sure the only reason she probably asks you to babysit is so you could spend more time with your niece. If she knew, I honestly think it would sting because this niece that you consider to be your “daughter” is just a chore to you. Do you ever think about her unlimited free babysitting of you since you were 7? She was not your parent and had no obligation to you but she took care of you because she loved you. You are such a horrible human being. YTA times a million. Please do your sister a favor and move out. Then even with daycare, she’d still probably save more.