Instead of charging your daughter rent under the rent a room scheme ask her to contribute to the household expenses while she lives with you. €500 a month seems reasonable.
You should apply for additional needs payments through social welfare where possible.
In terms of getting additional work, if you work at a venue can you try to get additional hours working at the door, cleaning, serving, usher etc. work in a coffee shop in the mornings if your art work is evenings.
Best of luck.