With a single-story house, you will hardly manage 170m² of living space, except with a high knee wall or large dormer windows (check the development plan for permissibility).
Oops, the single-story thing is only because the free software used only allows up to 5m.
It was actually just supposed to show the floor plan initially. With one floor, we very likely won’t make it within the building envelope.
I roughly showed in the site plan what remains for the house with a 3m boundary distance.

Thanks!
The 12x~10 should actually be sufficient, right?
We also have a (private) forest as neighbors and had to maintain a 30m protective distance with our building structure. Also, I am not allowed to build a carport or shed in this protected strip because it poses an increased fire risk. However, we did get approval for our terrace roof (ends 25m before the forest, so it lies within the protective strip), as it is made of glass and aluminum. The forestry authority always has a right to be involved when it comes to forest. At least here in S-H.
Is there such a protective strip in your area as well? It is regulated in the State Forest Law....
If I understood correctly, this property’s issue is more about trees/branches potentially falling onto the property without causing damage.
It is also only a fairly narrow strip of forest.
Where would you place the terrace?
North, North/East, East, South/East?