Why did you choose the black for harware? What is the plan for the shower ? I think figure out the shower either curtain or IMO a nice glass shower screen then maybe a nice frame less mirror and maybe black towels and white towels and add one color to that and then a piece of art with all those colors.

I’d do either your plan for mirror/art or put up a full wall of mirror and float your sconces thru the mirror - it wont be inexpensive but helps to expand the room and allows someone to use the counter for hair and makeup vs the sink area (plug for a hairdryer is at the wall by the door)

(Not suggesting this style)

I'd have a mirror contractor install wall to wall mirror.

If you retain all the black plumbing fixtures, consider not having more black in the mirror. If not the full mirror ideas shown, then a nice beveled frameless mirror above the sink.

Most shy away from black but with your hardware I would say it might be bold and rather dramatic, but beautiful to paint the wall charcoal/black. Then Add frameless mirror.

Otherwise, I would suggest you to use the frameless mirror everyone mentioned here and leave the black fixtures alone. Dont add more clutter, the black is heavy.

And here in your original just with gray and white striped curtain, and a track ceiling curtain rod. I would highly suggest you to swap out your fixtures to gold or nickel, unless you will go dramatic like my first example.

The shower curtain can be a strong design statement. Here are black and white bathrooms with interesting ones.

Using a full wall mirror could feel sterile and I don’t think the off balanced issue will be solved. Try taping out mirror sizes; it should be proportionate to the width of the sink, which will also help extend the area visually. Adding sconses will do the same.

Measure the remaining wall and find the centre for art (suggest two so it doesn’t feel lined up).

You could instead add metal shelving and if you can’t decide, test both ideas.

A strong shower curtain will pull the room together, but choose last.

go with gull wall mirror over vanity. room is narrow and full mirror will make it look larger