We have about this size and arrangement. Here’s what we have…plenty of light…

is that two total recessed fixtures, one over the bath, one over middle, and a sconce over the mirror?

I had read somewhere about shadows in the shower with just one.

It is. But it wouldn’t hurt to add another. No reason not to.

Ours has a window as well which is helpful.

Go with your gut feeling. All there is to figure out is if you want each different area and the bath fan controlled by different switches….

I found that I mostly regretted things the builder talked me into. You may walk into the bathroom every day and kick yourself if you don’t.

This is sage advice. I find that I have moments with tension with the builder.. oh this is what we typically do..and it just doesn't feel right...and then I waffle over it..tell them to do what I want..and feel guilty later on regardless!

Don’t feel guilty. I had many moments of tension. I feel like they sometimes try to steer you to what is easiest for their subs( or more money) I learned to be a bit suspicious and head online to research every time something didn’t seem right. Every time my garage door opens with paint still sticking together 3 years later… I think of how he talked me into getting white doors and painting them black…🤷‍♀️
I had them recess the door pulls for the pocket doors ( even though they were done to “industry standard “) because I could see they were going to mar the wall very quickly. Among many many many other things… I drove him crazy I’m sure. At one point he asked if I was an engineer ( I’m not) because he swore he’d never work for another engineer…hang in there. Listen to the builder… they have done this before, but do your research and keep asking questions.