For comparison: our utility room (cleaning supplies, washing machine, beverage crates, wine, cabinets for kitchen items that are not used daily, second refrigerator, freezer...) is larger than your guest room (a little over 12m2) and we also have a separate technical and connection room for all the technology, as well as another storage room under the stairs (for toilet paper, seasonal decorations, vacuum cleaner, etc.) and a storage room (bricks, paint, tools, suitcases, kids' craft projects, large decorative items like nativity scenes and Christmas tree stands) in the converted attic of 12m2. It really shouldn’t be any smaller.
Oh, and in my husband’s office – also larger than 12m2 – a lot of stuff is stored as well (spare school supplies, craft materials, books, kids’ memory boxes, photo albums, office stuff, etc.)
I honestly don’t know how some people manage with a 5+ utility room. I’m not someone who hoards, rather I throw things away quickly, but with kids, so much accumulates that you just can’t throw it away...
Otherwise, I quite like the floor plan.
And you can get a lot out of a small kitchen too. Maybe you’re already planning your kitchen in a kitchen specialty store, then you might still be able to adjust small things like windows, doors, etc. Otherwise, you might end up annoyed because the window is 5 cm too far to the left or something.