We have similar conditions as you. Net around 4,200 EUR, plus two company cars (already taxed), the jobs are crisis-proof. We financed 340 TEUR over 30 years – then we would be done (without special repayments), the rate is around 1,250 EUR p.m. One child has already been announced during the current renovation (toi, toi, toi). We can sleep well at night with that.
In the end, everyone has to keep a household book for themselves and decide if the rate fits their lifestyle. To me, it doesn't seem tight for you – you apparently have been able to save well so far. But a Maldives vacation every year in a 5*+ resort may not always be possible (the example can be replaced by other expensive consumer goods). Do you keep an eye on your expenses/kept a household book?
Btw. please let the woman switch to stage 3 in time when planning for children. Switch back when the child is there. Then there is more parental allowance, which is calculated from the woman’s net income. Some tend to underestimate/forget this. For us, that makes around 200 EUR p.m. with "normal" parental allowance (no parental allowance plus).