But! I've have a similar experience with showers and find them to be completely exhausting. I find moving from one task to the next in a shower to be extremely challenging as I kind of just zone out and disassociate hard, so my mom used to yell at me FOR taking showers because I was always in there for 40+ minutes. These days it's a good week if I get 2 showers in. (Luckily I have very clean skin and unoily hair so I don't look awful.) So you're not alone and this is a shockingly common problem with the people I know who deal with mental health issues.
Obviously you can't just jump in and expect it to be better. Instead I have some practical solutions I use to manage it. Sink showers are a big one where I wash my hair in a sink mostly clothed. I know a lot of people use dry shampoo. Sitting on a toilet is a great place to wash your privates and thigh folds with some soap and water that just flushes away when you're done. If you're changing clothes in the bathroom you can use the sink to help wash your armpits and other folds (like bra line or tummy folds). And you can of course wash your face and neck any time you use the bathroom. My theory is, if I can't get myself totally clean, getting even a little clean is better than not. It doesn't have to be 100% or nothing, you can break it down into steps, and how often do you REALLY need to wash your knees anyhow? If a shower is out of the equation for me and I wash up a little in the sink I am now infinitely cleaner that I would have been if I tried to shower and failed.
Also this is one of the few times I think bubble baths are appropriate self-care. If you can turn a bath/shower from a miserable experience into a less miserable one it can help. So playing music, running a nice bath with epsom salts, using fancy soaps, lighting a couple candles, anything that makes you feel better can slowly start to help build those neural pathways that take you from "showers are awful" to "I can shower and not hate myself after". It's not a quick fix but it's a little like CBT and it helps.
Maybe some of my solutions can help you with it, since it seems like you also wish it could be better. I really hope things start to get better and if you need someone to vent to, I'm here. <3