@Brentus I'm sorry to hear financially things are so hard right now for you and your sister. Definitely try to get subsidized housing. There's three section 8's-federal, state, and local. Apply to all of them because waitlists are crazy. At your local housing authority they may have some forms to fill out for other housing programs (public housing, specific project areas), and given your sister's schizoaffective she could probably get into supportive housing or a group home so there are some more options. There are also some private property management companies out there that do their own affordable and subsidized housing (I know here the cheapest "affordable" housing is over $1000/mo so I hardly looked down that route, but maybe your area is a little better, so do look into it).

If she's willing to work and capable, there are some programs that will provide housing if you work for x amount of months. Maybe with the right work she can manage that too.

Make sure you take advantage of everything out there. There are some places here that will help cover rent/utilities if you prove you temporarily need assistance. If you're not already on SNAP, apply ASAP. Take advantage of food pantries and such.

On sites like Nextdoor, Craigslist, etc. there are postings for odd jobs like pet sitting, yard work, baby sitting, helping someone to move, etc. you can look into if you can fit that into your schedule. Depending on where you live you can work for Doordash, Rover (dog walking/petsitting), Lyft, etc. to earn some.

If you're on SSI/SSDI make sure before you go out getting any kind of earned income you get into the ticket to work program though. It's a safeguard to make sure you don't lose all your benefits because you made $200 on your own once. Contact your SSA office about it. I got in it by going through my state's voc rehab.