The vanity next to the main sink is not drawn correctly. The sink counter height should be at 36" high (including countertop) and the make-up vanity height should be 30" (table height) if you want to sit in a regular chair. As currently drawn, you'd need a counter-height stool to use the vanity. There should be a line drawn to separate the counter height counter from the table height counter. Ask your designer to do an elevation for you so you can see what I mean.

If it were me, I'd lose the tiny sink in the WC, lose the make-up area, and put a 2nd sink in that's the same as the current main sink. That way, you and your partner can get ready in the morning at the same time.

P.S. You need a door on the WC.

Do you need a sink in the water closet? You can get rid of that sink and create a linen closet.

I do not agree to have 2 heights of cabinets and doing makeup at th a 36" counter only needs to have an adjustable stool to make this easy . It also gives you much more usable counter space . I hate toilet rooms no one should be using the toilet while someone else is in the bathroom and if you are not planning on the tub whay have this huge window in there at all. make the space smaller have a bigger shower and in my 60 yrs of marriage I hve never had a need for 2 sinks in my bathroom and actually bathrooms are not good places to store cosmetics . I would have that window not to the floor and put my vanity there with some fabulous mirrors made to hang in front of the window.This is agreat look IMO

1. although not my personal choice, but if you do intend to keep the toilet separate from the rest of bagno, you NEED a door (otherwise, what is the point? it is an awkward, waste of space layout), and you must have a small sink IN THERE. it grosses me out every time i have to use a toilet behind a door yet there is no place to wash hands! how does anyone suppose the person open the door to come out then? the word that comes to my mind is always "poopy"! and by the same token, please do not place any of your clean linens (aka your storage space) next to a toilet. 🙄 2. i also live in the US, where "double sink" seems to be the standard. i have never found any use of it - only gave me more to clean! more importantly, for an efficient use of space, make sure your sink comes with a big vanity where you can keep what you need on daily basis on the counter AND stuff you do not want lying around in the open underneath. i highly recommend one sink with extra-wide vanity that has drawers on both sides (one side for you, one side for your partner) or if your house is more modern, you can do open shelving with baskets. (see 2 pics, one is for my US home, one is for my IT home) 3. if i understood you correctly, the tub is not going to be there. well then, the answer to your question is easy: you can reduce the m sq AND have build ins (see the pic of my US home which is a design built as as well.)
   
   

Think about the location of shower head and controls, so that you don't get wet when turning the water on before you get in.

Double pocket doors is a waste of storage space in the closet. Eliminate one and you have wall space to hang robes, belts, purses, etc.

Why the huge window in a bathroom? If it isn't completely private and gets direct sun, you will need to buy blinds/shades.

I’m assuming the home has some pretty impressive views to warrant your architect designing floor to ceiling glass in front of the tub? If not— and you really don’t want a tub— the window is likely the greatest place for savings, but a change here could throw off the exterior elevation on that side. But I would question nickel-and-diming this space for what is clearly a higher-end home design. And, if there are great views to be had out the window, you may someday wish for that tub and/or want it for future resale.