My narcisist mom

Hello everyone, I'm reaching out for advice because I don't know where else to look.

For some context, I (M, 28 years old) am an autistic person from a South American family, living with my parents, one of whom, in this case my mother, is a complete narcissist (my father is also complicated, but that's a story for another time)

She's a hard-working woman, sweet in social settings, but she hides a very toxic side. One day she can be the most loving woman, and by the afternoon of the same day, she might raise her voice simply because her shoulder hurts. She might also develop a hero complex, wanting to fix other people's problems even if they don't need or want her help. But she can also feel attacked if someone says something she doesn't like, at which point she pulls out the classic Latin American mother excuse: "But I gave you everything, and this is how you repay me?"

The situation has escalated considerably lately. Due to health problems, she had to leave her job far from home because of a wrist injury caused by a combination of overwork and poor management. Because of this, she returned home, where she began exhibiting another toxic side: a combination of accumulating unnecessary things and an obsession with cleaning. And on top of all that, there's the situation with my sister, who isn't doing so well at university, which stresses my mother out even more.

My sister and I have become aware of the toxic atmosphere in our home, and we've always wanted to start a new life away from it all, each of us on our own. But both of us still need our parents' support—she for school expenses and I because of my disabilities. We've brought this up more than once, not as a threat, but as a way to get their attention and make a change, which unfortunately hasn't happened. This is another thing that upsets our mother and motivates her to continue her strategy of emotional manipulation.

I don't know what to do anymore. I've tried everything, from talking to her calmly, to seeking psychological treatment for both of us, to trying to build a space for myself on my grandparents' property with materials I've found, not to mention the countless times I've looked for stable work, even outside our small mountain village (I currently have a job twice a week, which isn't enough to plan for financial independence).

For now, my only refuge is my workplace and my occasional outings to nature, because I can't even have privacy in my own room due to the social rules of our culture.

Without further ado, thank you very much in advance. I will be reading all the comments and responding as I am able.

P.S.: Please excuse any spelling mistakes; I'm using a translator.

P.S. 2: My disabilities prevent me from doing physically demanding work or anything that requires dealing with constant stress.
P.S 3: My net monthly income is approximately $300 USD between what I earn at my job and a contribution from my country's government for people with disabilities.