Floor plan design of a single-family house with approximately 130 sqm living area

Admittedly, it is of course unfortunate that you have not planned any money or 40,000€ for the attic conversion. A ladder would be a no-go for me. I would rather pay for the staircase up and later gradually finish everything myself, then there will also be a second office.

The passage to the utility room/technical room has a width of 0.95m.

. . and it is not worth a penny. It is really shabby. Why not make the kitchen wall straight and create the access to the utility room there (under the stairs)? What is drawn there now is rather silly. The separate storage space under the stairs is also silly. What kind of door is that supposed to be? 1.50/1.70 m height?

I can only agree with my predecessors. And to add one more point ... 528 cm raw construction measurement for kitchen/dining is more than tight

60 cm tall cabinet row
110 cm island distance
100 cm island depth
.. that leaves 248 cm for a table with chairs, for which one normally calculates 300 cm. You also want to be able to get past the chairs when someone is sitting there.

And attic use for hobbies ... sleeping etc., only in the middle is there about 200 cm room height, the ceiling height drops off very quickly. And ladder from the office, a continuation of the stairs would be much more practical.

Your walking paths are somewhat quirky. You don’t go through the door and immediately make a sharp left like on a parade ground.
Also, the doors under the stairs are really a nuisance.

If the roof is not going to be permanently accessed anyway, skip the insulation and leave it as a cold roof. You’d rather invest the money in optimal living space. Maybe think outside the box for once (the size is approximately the same!):

The staircase is now considerably better.

As you can see, I have addressed many comments from the forum and think this draft works much better for a 3-person household than the original draft.

Yes, you have understood everything well and reacted accordingly.

Expanding as living space turned out to be too expensive (approx. 40K additional cost). The idea now is,

However, the situation is turning around. The double-wound staircase has of course become necessary because of the attic. If you can no longer plan with the expansion, then ’s idea would actually be worth considering.

Attached to the last proposal is an alternative for the upper floor. Here, a workspace is integrated into the bedroom. As a result, the rooms are less cramped and the bedroom can be repositioned to the east. However, the bathroom is above the kitchen - you would need to look into how to route the pipes.