You are blessed for what you are doing.
As a teenager I saw my grandfather suffer from Alz. It sounds to me that your Mom has dementia and not ALZ. In Alz there is a slow regression in time in the mind of the patient. He started showing weird behavior like running away from home, playing funny tricks on us, eventually he forgot how to dress himself, go to the bathroom on his own, even walk. He dies 8 year later in fetal position.
Your Mom is going through a normal part of her life and the best you can do for her is to go along. Try to talk to her as much as possible and take advantage of the good days. Forget the bad ones. Her life is not passing by. I can understand you wishing to make her life brighter, but it is hard sometimes. Also don't forget to take care of yourself. If she gets mad because you went out, she will forget about it soon enough. Get help and take time off often. I saw my MOm take care of my grandma for 15 years and never took one day off. It was not fair to her.
Take care.