Can you change the tub and sink fixtures to chrome? That would help to lighten it up. Even if you can only replace the sink faucet, the tub one would be hidden by the shower curtain. I like the white mirror and don't think it needs to be replaced. You could also do chrome hardware on the cabinet. Do what you have planned to the tub before you consider painting the cabinet. I would not paint the counter. Your flower pictures have a touch of neutral tones that might work with the cabinet and counter color. Good luck!

And the blue walls make the offwhite and creams look somewhat yellow. A pale sand/beige would look calmer with the color of the floor and vanity top. But that might be just in the discoloration of a photo.

Paint the vanity to a soft white, change the wall color to same. Then stop.

No you can't paint the counter, no you don't want a shower curtain over glass doors. If you want blue? Add towels. In blue

As a wall color in here, the blue walls are not your friend. You are in two palettes, warm and cool.

Actually, blue and brown work very well together, but maybe a bluer blue. and an even a darker brown for the vanity. Right now, there's a bit much going on, so I'd eliminate some of the colors.

I'd most definitely not rip out the tub enclosure or paint the counters.

I really like rinqreation's renditionwith a darker cabinet above.

Here's blue, brown white (which in my opinion would also work well with the dark shower enclosure).

Or all light with a the rubbed bronze

Or add beige

You are concerned about too many different things going on and now you want to another thing with a shower curtain makes no sense to me. Paint the cabinet the same as your trim and then see what else needs to be done maybe better lighting new faucets if you like chrome it adds a bit of sparkle,