Depression after notarized contract - experiences

In hindsight, I regret making so many compromises at that price (no daylight bathroom, narrow house), otherwise great location for the Stuttgart outskirts with a large plot (almost 300m2).

Shall I tell you a secret? This is currently the case with almost every property or apartment if you don't have an unlimited budget. I built my new house without a basement and without a garage. Of course, it would be nicer with those two things. But does that stop me from being happy in my new house? Certainly not. You should enjoy the things you have and not regret the things you don't have. That makes you happier in the long run. By the way, I come from the RT district, so I know what the conditions here are like.

A new apartment with the same square meters costs about 1,500-2,000 cold rent.

Calculate over 40 years with a rent increase of 1.5% per year, when will the rent be more expensive than the installment. You now choose a fixed installment/rent and have a very long time. And live in the house with fewer neighbors to your nerves and not in the rental apartment.

Get professional help. A forum is not the right place for (signs of a) depression.

A new apartment with the same m2 costs about 1,500-2,000 cold. With a bit less space, about 100m2, maybe also 1,300-1,400 euros cold. House fees often make a big difference. (...) (without financial worries, with nice vacations, without pressure)

So rent of 2,000 euros (or 1,400 euros) is okay for you, but not 2,000 euros repayment? Even from 1,400 euros, with an annual rent increase of 1%, in 30 years it becomes 2,695 euros. And then you don't even have property that you can sell in case of emergency. The rent is gone and pockets someone else. That should not be forgotten. If the house is not good in the long term, you can sell it again in a few years. If current prices keep rising like this, certainly not at a loss.

Also, with an income of 5,700 euros and 2,000 euros repayment per month, 3,700 euros remain, minus incidental house costs possibly 3,200 euros. That is, depending on how luxuriously you live, a lot of money.

House will be in Korntal

Thanks for the additional statements. I am also sure that there will be no problem with the payment. However, right now I only see the negative things, the fear outweighs everything else by far. I think to myself: Why the hell did I want to buy a house? The rental apartment is big enough, who knows if a second or third child will come (there is a wish for it). Wouldn't the apartment still be enough then? Will I even use the hobby room or garden that I have wished for as I always imagined? Do I even feel like maintaining the house and being married to it?

As I said, the wish was there but now it seems to have vanished. I wish to be able to stay in my apartment and still have enough money for all other things.

I am about to call the notary and ask about reversing the transaction. But 1. I will make myself totally ridiculous in front of everyone and secondly this might be a bit premature (how long would one theoretically have time to ask for a reversal if the developer agrees?)

I think better earlier, then maybe the costs for the registration in the land register won’t be incurred.

I am desperate and just want to be happy.

You are currently in a dead end.
The general practitioner can prescribe you “trial sessions” (6 in total) with a psychologist. Many people do that. It often helps.
Money is not worthless, you have the equivalent of a house. And you can live well even without a bathroom window. The location will be, like many things, a good added value.