Floor plan of new rectangular bungalow with 130m² living area

Any similarities to others can surely always be found.

I wanted to give you the hint: take a look in the "twin" thread, maybe some of the aspects discussed there will suit you as well.

We have the interior walls at 11.5 cm. 17.5 may make sense for some walls, but it does not contribute to the statics at all.

As long as we are not talking about KS, 17.5 instead of 11.5 makes the difference between "load-bearing" and "at best bracing". And you yourself said,

with a wall thickness of 36.5 cm the house carries the roof, so no further load-bearing elements are needed and you are free in planning the interior rooms.

... which incidentally is a misleading note insofar as the exterior walls, even at 17.5 or the 24 cm thickness which represents the standard at Town & Country as far as I know, already carry the roof on their own – the decisive factor is the roof construction (with trusses). This point makes the difference whether interior walls have to participate in the load transfer of the roof.