Ignore the design web-sites, they are selling an idea at a cost! I didn't want a clinical look so went for mermaid board in the shower area [2 walls of bright colour] and painted the walls in cream with cream towels. Our bathroom has a large window which gets the morning sunshine.
Pale paint can easily be re-covered with a different colour or half-tiled when you find some you like. Paint washes down without problems, I prefer bedroom paint rather than that supposedly for kitchen/bathrooms. We have a dimmer switch for the lights in the shower cubicle

Our paint around the wash basin needs thorough cleaning weekly and DH re-paints the whole room every 12-14 months. The shower area needs nowt other than cleaning, the mermaid board works well and is different.
Have you thought about large mirror tiles? Maybe paint from the floor upwards to shoulder level then some mirror tiles to the ceiling? They will reflect light. Small tiles can be bought on a roll like wall paper but is fiddly to fix! Don't let your 'fitter' dampen your plans!! this is what you have to live with.