Having a rough time

I’ve been living with my sister and her daughter for almost a year now. ( I’m 20 years old and I don’t drive because my parents never pushed me to learn and it is one of my biggest fears) I agreed to move in so I could watch her daughter while she was at work and she’d pay me, well after her and her boyfriend (the father) broke up and he moved out, she asked for me to get a job to help pay for bills ( I pay for all utilities and my own groceries and stuff). She also no longer pays me to watch her daughter. I could only work nights because I have to watch her daughter during the day Monday - Friday so I work nights at Taco Bell full time. I’m always exhausted. I watch her daughter from 7 am - 6 pm then work from 8 pm - 3 am and occasionally 5 am if the store is bad. I usually have to sleep while I’m watching her daughter and get up occasionally to feed / change her. (She’s 3, and manages to entertain her self most of the time and rarely gets into things.) Well I almost never do anything around the house because I’m always exhausted and my sister gets mad at me for that which I understand, but it’s hard to work up the energy to clean or help around the house. This has been a problem for awhile. Well my sister told me the other day that she’s deciding to sell the house and it needs to be cleaned and photography ready by tomorrow. She then later on texts me and tells me that I will not be moving with her and need to find a place to stay. I am now extremely stressed and have been crying constantly. I have no where else to go. I have no family that will take me in, no friends. I asked my boyfriend who also currently still lives with his parents and they said no. I can’t afford to live on my own, and on top of all of that, my sleep / work schedule will be interrupted because since we’re selling the house there are times during the day / morning where I have to get up and leave the house with my niece while people look at the house. I don’t know what to do, and I don’t make enough money to live on my own. My boyfriend said he’d help me as much as possible, but idk how much help that’s going to be.