@loganwahl, I think house sitting for your grandmother for most of the year is a great option. It would save you a bundle, help her out, and you’d be very independent. She may also know other snowbirds who need house sitters if she doesn’t need you, and that might be solution too.
CC is a unique group of very knowledgeable people about college costs and financing, but your parents, along with the majority of parents, just don’t know how much it costs, how to finance it, that kids can’t do it alone. Step-parent might be involved but may not have realized what they signed on for, or they have their own kids they paid for, or they had their own kids they didn’t pay tuition for and think you should do it yourself since his kids did. Just yesterday my mother was complaining that my nephew’s mother refused to sign for loans for him (he is the golden child to my mother, his grandmother). I told her that nephew could have gotten his own loans but he didn’t want them, so why should his mother? My mother, admittedly older and never did any financial aid for any of her children, had no idea that parents didn’t sign for the the Stafford loans, the students did. She’d been blaming former SIL but it was nephew’s choice to not take the loans.
I wouldn’t count on your mother coming up with money. If you can arrange it to live with your father to file the FAFSA through him, and then go to a state school, live at your grandmothers, you might have a plan that will work.