I have now read through everything - interesting.
We come to about 4000 +1800 fixed per month. For me, there are almost 1000 more per month from side jobs. A few earnings from dividends & interest. A family-friendly company car, which already reduces these costs. Plus an annual bonus between 500 and 1000 euros calculated per month.
Because of the child, we have about 2000 less than we had before - about 1000 less salary and about 1000 more expenses.
I would have no worries up to about 2000 euros installment (repayment + interest).