No one can help you in a vacuum. You need to provide info and details.

Can you upload a photo of your bathroom?

I think I have a technology disability.

The 40" mirror would work. But I think there are some better options.

see if you like any of these.

So do a full mirror (either framed, or a beveled edge) over the entire countertop.

basically like this,

then get a wider light (that one you have is way too small) and have it centered over the vanity. (not the sink) .

You want it like this. (and I don't like any of these products used, i'm just showing you it for proportion) .

this is basically how your 40" mirror would look over your vanity.

if you want to keep the light centered over the sink, then just do a mirror that fits the space over the sink. Like this

a wood framed mirror would warm up the space. I like the open niche w/wood shelf too. You could do a more modern light that works with your decor. but center it over the vanity

you could also do a lighted mirror and avoid lights overhead

you could also do a round one and place a little wood shelf over the other part

kind of like this, but the shelf would be moved over to the left and attached to the wall

or, mount a full mirror, and still do a wood shelf all the way across. I love this look. (not this light) Think about doing a lighted mirror and avoid the overhead light. side light mirrors are more flattering anyway

I like this set up. lose the towel bar on your right and do an inset open niche like this.

I prefer lighting that is at the side a bit above eye level rather than overhead. You don't have to look at bulbs and it doesn't create shadows. It should not be difficult to have an electrician move the wiring.

Thanks great suggestions.

If you plan to apply makeup in this space, do NOT use lights above the mirror as your only light source. They cast shadows and accentuate skin imperfections. I prefer a ceiling light, perhaps as part of a ventilation fan, along with sconces placed on either side of the mirror. Much more flattering and much easier to see what you are doing when doing makeup!