Have you considered getting a pedestal sink with small free standing storage nearby?

Yes, I thought about it and feel I would lose all the counter space that I currently have. My young adults really like the counter space.

I agree with yoru contractor that a 3 inch space is not a good idea. i had a vanilty woth 6 i ches on either side and all it did was collect dust and i drop things on the side occassionly. Couldn’t you use a curtain with liner if you wanted and just push it to the beginning of the vanity? Or put it inside the tub and just launder it more frequently than usual?

i don’t see a way to address the tub controls unless you move them which would require a new tub or if you have the vanity custom made something like you current vanity where either the sink sits out further or just leave the cabinet adjacent to the tub at 15” deep while making the balance of the vanity deeper.

@maureen214 Thank you for the suggestions. I am going to look into making the vanity 15" on that side only. Not sure if that will look odd but it seems like a good idea to look into.

The tub & vanity could use some breathing room but at the same time you don’t want to give up counter space. I would look for a large console sink with some counterspace, this one is 37” wide, there may be slightly larger ones.

https://www.wayfair.com/home-improvement/pdp/kingston-brass-ceramic-rectangular-console-bathroom-sink-with-overflow-lbnf4008.html?piid=49642638&experiencetype=2&selectedvertical=3

a small shelf between the 2 windows above the faucets would give a little more surface like this one:

I think a much smaller vanity would be really terrific! I have strange bathroom dimensions too, and there was this odd custom vanity that was meant to maximize storage. After much, much deliberation and agonizing about losing storage space, I finally decided to get rid of the old vanity and just get a smaller one -- and now I'm really glad I did. Mine is only 24" x 18" deep, and it's got three drawers so I can still fit major necessities in there. And we found a little floor-standing metal shelving unit at our local Homesense (like a Marshalls) which is absolutely perfect -- it provides extra storage space right next to the new vanity; it can be easily pulled away for quick cleaning and it helps lend an openness/airiness to the otherwise-cramped space.

I think a 36" (or wider if it fits easily) x 18" vanity can look great in your space! Here's an example from Home Depot, although if you're getting yours custom made you could add drawers etc:

If you go with a smaller vanity, then you could also put a "rolling storage bath shelf" like this one beside it, which would solve some of the problems you identified including being able to access for cleaning:

:)

wow what a very creative idea to have a rolling bin that looks like its not on rollers! I like that.

It looks like you may have room to turn the vanity and place it on the wall so it's parallel to the tub? Otherwise, maybe a full depth vanity that is about 2/3 the size of your current one, so it ends in line with your window frame. You wouldn't be losing that much countertop space since you'd be gaining some depth, but it would give you extra space near the tub. If you do that, I'd keep the sink where it is so it would be off center on the vanity.

I'd keep the vanity short, get it custom made or just paint what you have. You can use an outer shower curtain if you trim it to bathtub height near the vanity. We had an awkward arrangement of that sort in a former house and cut a section of shower curtain to be shorter. It's an easy sewing project, so would be cheap to outsource, if you don't sew.