Floor plan single-family house, 3 children's rooms, goal: save sqm

Hello dear readers,
I hope to find some suggestions from you here for our attached floor plan.

We have purchased a plot of land over 900 sqm, flat, without a development plan (so no requirements, only the normal 3-meter distance to the neighboring property).
The plot is 24 meters wide towards the street and 38 meters deep.
So actually plenty of space.

All our wishes were perfectly implemented.

But unfortunately, we are now over 215 sqm... 190-195 was our goal.
Now we are significantly over, but I can't find a proper solution...
The vestibule could be smaller.
The OH office doesn't need to be 19 sqm either, but the problem is that you can't just take away 5 sqm somehow... The ground floor and upper floor must fit together again...
10 sqm would be enough for the bathroom.
Office and every children's room are enough with 15 sqm, the double hallway upstairs is not important to us either.
The vestibule is also enough with 8.
So mathematically I find the errors but in implementation... Help...

Meanwhile, I am in a building bubble and everything now revolves around the floor plan... And my phone is full of screenshots full of furnishing ideas... The more ideas, the more complicated it somehow becomes. Who else feels the same?

If all your wishes are perfectly implemented, have you already considered whether you want to build in that size?

Hello!
Are you still filling out the questionnaire?
Otherwise, I'll just say: one office and one children's room gone, then the house is reduced

I can't find the 3rd children's room mentioned in the title anywhere...?

If all your wishes are perfectly implemented, have you already calculated whether you want to build at that size?

According to our developer, the square meter costs about 2600 euros. And now we have exceeded our budget and you have to plan a bit more anyway and then it simply becomes difficult... Unfortunately

I can't find the 3rd children's room mentioned in the title anywhere...?

Sorry... It's currently being used as an office. We have 3 children's rooms upstairs and the office downstairs.