Building with a small budget feasible?

Nothing from nothing is nothing.
You have to be able to afford 85 sqm first.
And if you can't afford 85 sqm, you end up with nothing again.

I can understand you too. But sometimes dreams can't be realized. If you were in your early 20s, I would have understood the daydreaming.
But at your age?
And with your income?

I myself work as an educator in the mornings and as a childminder in the afternoons and dream at night of craft scissors and scraped knees. So any renovation / conversion with simultaneous full-time work would be out of the question. At least for me. For you, it might be different.

We would basically have had to move every wall. The upper floor would have had to be enlarged at least with dormers.

Hi, what's so bad about that? It doesn't all have to be at once and immediately. Better a small, not so perfect house that you can gradually make nice than something much too big that doesn't fit financially. See with Jana... Regards, Olli

What exactly is your goal? Would a property further out, somewhere on the edge of the village, not be interesting? There are only three of you, the child is no longer that small, the budget is tight. I can understand that you don’t want a house without a garden. I would keep looking. I would stay away from new builds. At your age, I would definitely try to keep the loan as low as possible and really assess the whole thing realistically. The question should never be: What does the bank give me? But: What can I really afford in the long term?

I see exactly the same. Apparently, there is indeed a certain selection of existing houses that can be renovated. But extending, adding new dormers, and generally a complete renovation can go wrong even faster than a new build.

With the mentioned figures of repayment vs. rent, you must not forget that maintaining a house in monthly expenses does not consist solely of the repayment. Additional costs are significantly higher alongside electricity, gas, water, trash, taxes, chimney sweep, maintenance, and so on.

Honestly - is rent at 75 really any different? And that works for tenants (who are 53% of Germans) as well.

I’m not talking about American conditions now. Buying, financing flexibly, and then paying off the loan through the sale and pocketing the appreciation. I’m talking about a reasonable setup with maybe 25-40% loan-to-value ratio. What could happen there that can’t happen to you as a tenant? As a retiree, you can no longer become unemployed ;-)

I can only repeat myself and fear that we simply won't find a common denominator.
My already retired parents-in-law live in a terraced house built in '79, where almost simultaneously the oil heating had to be replaced and the flat roof renovated.
If I imagine that they couldn’t have built up sufficient reserves because of an ongoing repayment, then financially it would have been tough with his electrician pension and her housewife pension.
Shortly afterwards, something was wrong with the car as well, again around 2,000 euros gone. You get into a tight spot faster than you can blink.