Floor plan of a bungalow with 140 sqm - does the storage space fit?

It would then create an area of about 15 sqm. 10 m in length and 4.8 in width, I will upload pictures shortly

carried this out and has experience with the storage area

That was explained by like that and also experience with the storage area

I don't find it that way. It was about bathing the children.

That was explained by along with experience with the storage area

That was in post#8

These would be the costs for the attic. Currently, we have a non-convertible attic and thus, of course, less storage space.

I don’t understand that, and I’m also not sure whether you understand it or if you and your builder are talking past each other. When the forum talks about an attic, it means a roof space that can ideally be fully accessed to be used as storage; and by convertibility, the (not given here and not needed) possibility of making living or even habitable rooms. I don’t recall whether your ceiling beams are fully covered with rough boards or the like. That would be beneficial because you could also use the areas with less than one meter height (light blue area) for boxes with Christmas decorations. If I remember correctly, you got the suggestion to upgrade the roof trusses from timber frame trusses to studio trusses, which at least makes crawling through easier. By the way, personally I wouldn’t have chosen an expensive hip roof here but a gable roof with the same pitch, and also designed it open at the ridge above the children's rooms and the dining/cooking area. Overall, that should be roughly budget-neutral. Using your brain leads to better building without making it more expensive.

What I meant is that currently we have a roof that cannot be expanded because these roof trusses are in the way everywhere in a zigzag pattern.

Therefore, I have now requested studio trusses (as recommended here), which I can expand in the ridge area. The just over 5000 euros are the surcharge for this.
I will keep the hip roof areas as non-expandable. Our house provider has a hip roof planned for the bungalow. We also like it better visually.

We also have these non-expandable rafters. For storage space, that is completely sufficient for us. I have laid floorboards over about 25 square meters. Small cabinets and boxes were then placed between the rafters. In the middle, I can just barely walk through. We keep summer/winter blankets and shoes up there, my husband's CDs, toys and items for the next grandchildren, vacation motorcycle gear. Only things that you only need to access every few months. I would not have paid an extra 5000 euros if you only have a floor hatch anyway. I wouldn’t want to go up there all the time anyway.