So if you want to stick to the budget, I would:
- Leave out the balcony. If you have a terrace, you will never sit there, especially if it faces the street.
- Leave out the studio and roof terrace. The same applies to the roof terrace as to the balcony. In our neighborhood, four houses have a roof terrace and all residents unanimously agree that they would not build it again because they always use the normal terrace anyway.
- Leave out the "Relax" area. You have a large living room. Instead, I would make the children's rooms bigger and place the small bathroom upstairs between the children's rooms. The toilet, sink, and shower are directly adjacent to your bedroom. If one of the teenage children comes home late at night on weekends or has visitors, you will hear everything.
- You have three showers. Two are more than enough for four people, who will soon be fewer.