For the walls: SW6476 Glimmer, SW6210 Window Pane, SW6211 Rainwashed, SW9611 Minimalist, SW White Sesame, SW9503 Cheviot

I like those colors for the walls, would you keep the cabinets white?

Yes

I would take down the framed mirror and have a wall to wall mirror installed to expand the space

I'd add recessed medicine cabinets to either side of the vanity to hold all the necessary sundries needed in a bathroom. The cabinets fit between the studs. Just find the studs, but the rectangle with a drywall saw and the cabinets slide in.

I would install a closed door kitchen wall cabinet above the toilet instead of shelves. This way the stuff inside doesn't need to look perfect all the time and frankly you need the storage.

Figure out a way to address the kitty litter box. Lots of stuff on the market to hide it.

Since your cabinet is lower than what is typical now, I might consider replacing the sink and faucet with a sink that sits both above and below the counter to raise the height of the sink.

A single hole faucet will go a long way to updating your bathroom.