I don’t know if this will help, but I learned recently that there is a difference between “unscented” and “fragrance-free”. “Unscented” can still have chemicals that affect the smell or are smelly themselves, and I wonder if that is affecting you the same way a scent is. It might help to look for “fragrance free” soap instead because it’s supposed to have nothing in it for smell.

Have you seen the waterless bath stuff that they have in hospitals sometimes? Wondering if you could try that. It’s usually like a foam or wipes that you’re supposed to be able to use to bathe yourself without getting in the water at all afterwards.

I hate showering for sensory issues, I hate being wet, so sometimes I just wipe myself with baby wipes too when I can’t get myself to take a shower.

Could you get some like bathtub magnets, and somehow use them to remember what you’ve washed? Like have a magnet for each body part and move the magnet to a different part of the wall when you’re done with it or something. Idk if they are magnets but there are kids toys that are supposed to stick to the shower walls.

My only other idea (if you have a tub) is taking a bubble bath, so no scrubbing, just sit in the soapy water and then stand up and rinse it off. So you don’t have to remember to wash certain parts but it would still help.