I spent two years living with my parents to nurse my father back to health. My sister made excuses to get out of it by saying she was ill and then her husband was ill. This was a lie. When my mother got ill after my father died we agreed to alternate days. I was ADAMANT that I would help out but would not move back full time. Seven months later, my sister faked a back injury. When that ran thin, she moved onto stomach issues and refuses to come back. How do you force someone to accept responsibility without starting a war?
I am sure the daily responsibility is draining on you. What sort of care does mom need? Is it really daily? Think about hiring a companion, on mom's dime, for the times when you cannot do this. You need a break. Perhaps mom would do well in assisted living, then you can visit when you want as a daughter, not a caregiver.
I see you asked a similar question back in October. Review the answers you got there. Responses are going to be the same here.
https://www.agingcare.com/questions/how-can-i-cope-with-two-sisters-who-are-ditching-their-responsibilities-and-have-left-me-holding-eve-452812.htm?orderby=oldest