I just want to clarify that this is the slab floor you're talking about and not something you are adding to a raised foundation? If that is right then it is a cheap solution and may be fun to do. Adding a laminate wood or carpet later is possible but in the case of wood laminate could result in the big chubby extra trim around the base moulding which a floor done by a good floor guy in the original buildout won't have to add.

You could do a wet room on the south end of the room with the tub and shower combined to conserve space. Window would go above tub, however with privacy in mind it would not be low as you have in your cad drawing. see photo. Vanities would go on the west wall with toilet on the east wall. I am guessing at the dimensions because you mention meters and in the US we use feet, but it sounds like about 9'x15" ? The location of the entry door really impacts the layout of the room, but it looks like it cannot be moved.

Thank you. My husband and I chose the tile (per recommendation at the tile store) and used a professional tiler (per recommendation at the tile store) for the install. It isn't a flip. This is a family home that we purchased and spent a year renovating—not DIY but with all professional hired help and a contractor to oversee the job. This tile person wasn't hired by him, though, as he was happy to use the person that we were told was very good by the tile store…. My heart is sinking. I absolutely hate the idea of retiling the shower as there is matching tile on all walls, including shower. I'm hoping there is some other idea out there that will help. I do personally think the tiler should have informed us if the tiles we supplied to him weren't suited to be mitered…we discussed it even before tiles were purchased and he didn't mention any specifications. I'm just worried now that if we put it on him to fix it, we'll end up with a bigger mess...

I have to ask, do you really need that bath when you have such a tight space? Unless you have tiny children (and remember that's a temporary situation!,) I suggest a larger walk in shower e.g. 1200 x 800 and heated towel rail on the wall nearer the window so its more convenient. Would definitely keep the double vanity for those busy mornings with storage under and you could add mirror fronted cabinet recessed into the wall above the basins to add more storage. Hope that helps!