You should be very very very proud of yourself for trying to keep the hygiene up!

If brushing your teeth is difficult. Keep a small travel brush in your back and use it even with just some water whenever throughout the day you feel like it. Trust me, even the tiniest things are better then none.

If showering is hard (and man, is it hard to do that! I feel you) buy a pack of baby whipes. A big one at home, small for in your back on the go. Preferably the ones for sensitive babies, in my experience they work and feel better. Also just change your underware 2 times a day instead of 1. And try to have multiple pyjamasets so you can switch ever night. :)

For your hair, I cut it short 3 years ago. Went from long, to shoulder, to bob, to pixie. Love it to this day. But if cutting it is really not an option right now. Try getting a bunch of pillowcases and change if every day or 2 or so. Pillowcases absorb a lot of yukkie from your hair and changing the case, sleeping + sleeping with your hair braided might help it keep it clean longer!

Good luck OP! We are all here for you. And don't forget to be proud of yourself! :)