Hi Ashley,
I’m sorry you’re in such a difficult situation – your dad should never agreed to letting you have a rabbit if he wasn’t prepared to look after it – that is part of a parent’s duty when they let a child have a pet. It’s clear that you’ve tried your best in a difficult situation.
To be honest, its going to be difficult to litter train an unspayed, 7 year old rabbit. Often unspayed rabbits are harder to train, as they’re driven by hormones, and will pee and poop to mark territory a lot more. Can you tell us a bit about what her set up in your room is like?
The best thing to do is to have a litter tray, with a distinct ‘litter’ substance in it (I use paper based pellets, but cheap wood stove pellets or non-clumping wood cat litter are also good options), and to not have other bedding in her area. If you’re worried about her being on hard flooring, you can give her a fleece (as long as she doesn’t eat it) and chuck it in the wash every few days. Her hay should be in or next to the litter tray, as they often poop while eating.
I also think, as hard as it may be, you need to start considering what you’ll do with her when you move away. Perhaps you could start looking for another home for her, or even research non-kill shelters. Its obviously not safe to leave her with your dad, and you might feel more reassured if you had a plan for her.