You could use this great looking tile as your vanity splash back, your shower recess or rear wall and use a standard lower cost coordinating white tile as a secondary filler. Like he main walls in a satin rectangle laid in a stretcher bond like a giant subway, rectified with minimal grout, and then this gorgeous tile with a mid grey grout to emphasize the fantastic form. It would make for higher impact of the feature tile, and add functionality by fully tiling all areas. Easy to clean, reduces moisture related issues or even just unsightly condensation and cleaning scenarios. Mould retardant additives can be put into standard paint, although in a bathroom, I'd go a low sheen white with mould retardant for this reason. Low sheen should be flatter than satin, little shine at all, but equal to a matte tile.

Absolutely agree with blueskies60 ! Remove the artwork/bench/plant that's on the left and replace then with either a bookshelf or a tall chest of drawers. Perhaps the plant can be repositioned into the corner on the floor where this troublesome niche is (there seems to be more than enough light there for a plant) and just place something calm and simple in the niche itself - perhaps a Japanese style scroll or pen and ink art work set off with a more rounded object sitting in the left corner of the niche; a gorgeous rock, a lovely candle, a calming statue... If you have (my preference) a chest of timber drawers on the left where the current art work is, you'll break up the symmetry, have more storage and have another surface upon which you can place a changing display of objects. This is the area that I would utilise for a mirror.

have a shorter recessed wall cabinet for storage and if necessary have the balance of the space fixed mirror.....you should find something suitable at a fraction of the cost of custom made but strongly suggest that you don't have the vanity hard up against the glass screen (a gap is useful for hanging a hair dryer or hand towel and allows easier access to clean the glass screen) we've been disappointed with custom made vanity and wall cabinets which were more than twice the price and no better quality

Your renovations are well underway, so after seeing the small floor plan and that the vanity is on an internal wall and you apparently still want the Shaving Cabinet. Having cavity brick walls I would get your brickie to remove a section of the brick wall so that the shaving cabinet can be recessed back into the cavity, this will overcome any concerns you have about bumping your head, this opening can then be patched along with other walls. I would take all of your photos and measurements to someone like Reece to pick a hand basin to fit,, I would also keep in mind that if say the width of the vanity is around 900 the shaving cabinet would match that width and you would end up with say 2 x 450 mirrored doors, which puts the mirror join in the middle and in your face when using the vanity. cheers