I think you need to watch tiling videos or speak to a professional.Hmmm... What I described as 'slivers' I anticipate needing to cut (shave) off a tile would all be thinner than 5mm - perhaps down to 1-2 mm.
In a tiled bathroom there's no way to need 1-2 mm shaving.
Also there should not be any cuts exposed, unless you are staggering the tiles like brickwork and adding a vertical feature like mosaic.
I explain: in corners you'll overlap the tiles, so the cut edge is behind the tiles from the adjacent wall.
Around door you can go as crazy as you want, architrave will cover any cuts.
Around windows recess you'll use a trim, again covering the cut, even if chipped (easily done with wet cutter).
Ceiling line can be easily covered by coving, looks better and gives you 90mm to play with.
Floor tiles edges will be covered by wall tiles.
I don't see the need for the 2mm shaving.
Even if you end up long (and you shouldn't if you've planned properly), you could use smaller spacers to work that out, although I never needed to do that.
Planning the layout is key.