Hello @a_2023 and welcome back to the Wefugees Community!
It is indeed not easy to find an appartment in these days - especially with a bigger family. I recommend you to contact a refugee/migration counselling office for support. They might not be able to find you a house directly, but they can explain you the procedure and give you advice on how to find accomodation. They may also refer you to an office/service/organisation dedicated to this type of support. To find a refugee/migration counselling office in your area, you can use this search engine.
Handbook Germany collected some very useful information on this topic as well.
Good luck and don't hesitate to keep us updated or