Financially, I am also rather on the skeptical side. Of course, the installment is basically manageable with the current income and with one child. But I still see some risks and a lavish house that does not fit with that.
170m2 plus basement for 3 people? Very comfortable. I don’t quite understand why home office is listed as an argument here, which according to your own statement is only used once a week anyway. Having a completely separate room for that (unless it is tiny anyway) is actually not in any economically sensible relation. You can always fit a desk in a house for rare HO exceptions.
Even for 4 people, 170m2 is still generous and 10m2 less would still be fine. Always keep in mind: you still have a basement and 2 garages (unless there are 2 large SUVs parked there and not at least one smaller car) as storage space.
But regarding the financials:
What bothers me critically is the strong income difference. Could this also be due to tax classes? If not, then you simply cannot compensate for your husband’s failure. Illness or job loss and you have a big problem and the house must go. Your 100% income is simply too low for the installment. For that, you would need significant liquid assets in reserve. But you don’t have this, because everything goes into construction and the kitchen.
Ingolstadt. Let me guess, the husband works at Audi? What happens if jobs get cut (Audi has been lagging behind for several years)? Then, in the worst case, not only the job is gone, but at the same time the value of the house is in free fall (everything depends on Audi there). This is called wrong way risk. Although you have invested a lot of equity so you probably wouldn’t have to file for insolvency, in a forced sale your actually substantial assets would still quickly be largely at risk.
Even if nothing goes wrong (let’s hope so), you are constantly in the hamster wheel with this installment and it necessarily means work instead of time with the family (then possibly with 2 children instead of just one). Not a good feeling. Honestly: plan a bit smaller, maybe also some improvement on the interest side and you get an installment in the lower 2000 range. That way you can certainly sleep more freely. 20 hours of work with an eight-month-old baby? With our child that would have been unthinkable. Much too clingy etc. I would therefore not necessarily assume that it will also work like that with the second child, especially if you already have one and you are also a few years older again (and therefore less resilient).