Not sure if I can take this any longer. What can I do?

Where do I start! So, my mom was diagnosed with having a complex MBI, back & neck injury. She can’t walk on her own, has to be holding onto someone for it. Frequent dizziness. Can’t stand or sit on her own, balance issues. Hunches over a lot, can’t fix her own posture. Sometimes she can lift her head up a little but she forgot how to straighten her back. Has charley horse, insomnia, and moves in her sleep so much that at night I get called every single hour if it isn’t every half hour, or minutes divisible by 5! Just to adjust her position, stretch her leg, flip her over, maybe even walk her, or (and this is definitely by each hour) take her to the bathroom. Did I mention urge incontinence? She’s been getting weaker, but she weighs nearly 60 pounds more than me and I am.. small. I’ve been at this for months so I have gained muscle, but not enough that I can lift her too much.
Been caregiving since spring, can’t say I remember anything before July because that’s the time I came back after a 2 week long vacation that I planned months in advance without the situation having been this severe. Couldn’t go a few days without being guilted by their calls. Turned into an adult this year. Pandemic & mom was a recipe for getting held back, so I haven’t graduated. Can’t attend regular school anymore, let alone make time to do simple assignments. My family only consists of my mother, older sister, and my sister’s partner. (Nobody else if you don’t count in-laws.) The latter 2 work night shifts at grocery stores. I’m unemployed, don’t know how to drive, how taxes work, what resources to look into since I can hardly do complex tasks… If it’s not executive dysfunction from depression alone, I suspect myself of having undiagnosed ADHD. We’re also uninsured. Given this background, I’ll explain what I go through.
Every waking hour = tending to my mother’s needs. Only if my sister isn’t gracious enough to bestow approx 2-5 hours of letting me sleep, if she sees herself capable of it. I take naps between intervals of tending to mom, switching out one need of my own for another, if not rest it’s eating, calling a friend to stay sane, can’t shower for too long, I forget to brush, etc. This small apartment belonging to my sister is NOT fit for mom in her condition, I can’t shower her without it being a life or death situation from lack of balance and my sister refuses to get a bench cause she says mom needs to stand up more and sounded like I *want* her to stay the way she is by sitting. You know how insensitive that is?! She reeks and when my sister offered to help me with the showering, she didn’t help at all. I got forced to do it that day alone while sis recovered from COVID. (But she was clearly well enough that all she could’ve done was put on a mask around us.) My mom is hardly active anymore, sitting around using her devices, mainly this big TV in her room that she’s barely a few feet apart from. I tried managing her nutrition and keeping her away from devices (doctor’s order, too,) but she was so whiny about me trying to detox her from sugar that I didn’t fully win, we compromised by only keeping *most* sugary things out of the way. Still doesn’t count as detox. Still looks at her devices daily. No one really listens to what I say, no matter how right I am. Toilet clogged, I said it was the loose handle and sis refused to call the office for a week. I was right. Dishwasher clogged, my sister always says “it never cleans well,” I tell her to rinse off food before sticking dishes in, she didn’t. They don’t care about the little things I suggest to make recovery smoother, they like to forget the point if it doesn’t help enough. Mom is stubborn and my sister.. is not very bright. She left me to take care of mom for two weeks alone too. Big difference leaving 2 grown women to do this VS. me, only having emergency contacts. Real telling that I did better than them.
All of this I put up with, and my tolerance fluctuates. Don’t know what to do!