The floor plan proves to be poor during the shell construction

Well, then show a site plan of your property and the surrounding ones.

Can the garage be positioned differently?

Although the question is, if no additional window openings can be made, what do you expect could be changed?

The garage could possibly be positioned differently and windows could be installed after construction. The 5-year warranty from the construction company would probably be questionable if something is changed immediately.
Attached is the site plan.

Adding windows afterwards (the shell construction is done) is not done by the construction company without stopping the construction for 3-4 months

That’s what the general contractor says - ask the craftsmen on site if they don’t want to earn a few extra bucks on the side ;) . Then you’ll get an additional window very quickly.

If I were you, I would grab the shell builder. Ask him what it would cost you to additionally install a lintel for a window in the living room on the south side. If he says yes, it’s possible, you go back to the general contractor and tell him that it’s no problem to add the window, and then you give him a good cry.

That’s pretty much how I would do it too. Just talk to the foreman on site, provide an appropriate tip, and the masons will manage to make the change.

Which changes make the most sense now, you can probably judge much better on site than we can without a site plan, photos, etc.

My experience is that you can still change a lot during the shell construction if you want to ;-)

Exactly. First of all, the question is what you want to change now? Otherwise, just let the house be finished first and don't put the garage on the south side. Then later, after the construction is finished, put windows in there and that's it.

that was also my consideration

Exactly. First of all, the question is what you want to change now? Otherwise, just let the house be finished first and don't put the garage on the south side. Then later, after the construction is finished, put windows in there and that's it.

that was also my consideration, but I don’t know how complicated it is after completion. Whenever I want to change something, like put a drain into another room because I only thought of it later or make a window half a meter bigger, they say nothing can be done. That really annoys me.

I would do it pretty much the same way. Just talk to the foreman on the construction site, provide an appropriate tip, and then the bricklayers will manage to make some changes.

Which changes make the most sense now, you can probably assess much better on site than we can without a site plan, photos, etc.

My experience is that you can still change a lot in the shell construction phase if you want to ;-)

The men who did the shell construction came from some other city and have already moved on. It will no longer be possible to reach them.

First of all, stay calm, sleep on it, everything will be fine. The house is certainly not completely ruined just because a few decisions were suboptimal. They say - you build your first house for an enemy, the second for a friend, the third for yourself. We have now reached the friend. ;)

We also stood in the shell construction today and thought "OH damn, it's so dark in the place," but that will get better too. We are building for the second time and somehow everything normalizes. The lighting conditions, and also the sometimes bizarrely appearing room sizes in the shell construction. Walking around on the floor slab and thinking "there’s no way this is X square meters" is a completely traditional experience for future homeowners. :)