Building a house - Is the budget for building a house okay? Who has experience?

So I haven't kept a direct household budget for about 8 years, but I have a separate account where I transfer money for groceries/ drugstore. I work in field sales and like to make a stop at Lidl in the morning to buy a fresh roll and a pack of sausage or cheese. In the afternoon, we eat a warm meal at home and in the evening there's a few nuts, slices of sausage or cheese, and some quark. My wife has homemade open-faced sandwiches at work and eats in the cafeteria. Son (1) has open-faced sandwiches, lunch at daycare, and dinner at home. And I can say quite precisely: Current amount including diapers is 450€ per month.

Sure, it depends on one's own needs, e.g. meat from the discounter or butcher, same with bread.

Sure, yes. In our case, almost no meat, I wouldn't have thought that makes a difference, maybe there are other reasons ... Anyway .

I'm not doing the kitchen and bathroom myself right now... these are where the fastest wear and tear occur....