Can anyone help with advice?

Hi

I'm the mother of an adult daughter diagnosed 3 years ago. She has an 8 year old daughter and they both live with me.

My problem is that she is very untidy, verging on the dirty. Her bedroom looks like that of a messy teenager but she's 34. I never go into her bedroom, she doesn't like anyone going in there, but sometimes the smell is quite bad. I do all the house work and her daughter's washing. Otherwise her chaos would take over the house and the little one would have no clean clothes. Her room can be full of dirty dishes and I have to ask her to fill the dishwasher when we run out of bowls/plates! I get attitude from her when I do this.

She spends a lot of her time in her bedroom and can have very little interaction with her daughter. It's not just lockdown, she's always been this way. She does live her daughter very much and i know she tries hard.

I'm 63 and get exhausted trying to keep things as 'normal ' as I possibly can for my grand daughter and stop my mental health from deterioration. The little one has asked me why I always look after her and do all the housework. She's starting to comment that her mother is very lazy, I have no idea how to respond. I've suggested to my daughter that she explains her diagnosis to her daughter but as yet she hasn't. 

Please can anyone help me in how to deal with this? How can I get her to feel better about herself and get motivated? Is this unusual behaviour at this age? Thank you so much for listening.