Floor plan optimization of a single-family house with a basement on a small plot

Would plan a large open-plan kitchen on the ground floor and separate the living room with a sliding door.
That is not what the OP wants. Still, worth considering.

Family life takes place at the dining table and in the kitchen.
The living room is a retreat and can, for example, provide enough privacy for guests.

Oh, that was our idea with the bay window, but it will probably be rejected as well

New construction is expensive
The bay window costs a lot of money

New construction is expensive The bay window really costs money

All right then, that's probably out

First, draw the parking space!

No, as I read it, no parking space is allowed on the right within the 3m distance.