I think it CAN be isolating as a parent without paid employment (are you a trailing spouse?) and few language skills in Germany. I learned German within a year of arriving - but then I was young and single, and I was able to immerse myself thoroughly into the language without having to consider any children's needs (could just go to a local Kneipe and meet up with people there). Many other people arrive single and then meet their future partner in Germany, so that automatically integrates them into the local society.
I take it your children are not attending an international school? Mine are at a bilingual school and many of the non-working mums do voluntary work at the school - being Klassenvertreter, helping out at events, reading books, etc. But I suspect solely German schools have less parental input. And I've heard people say that SOME small German villages can be rather, erm, exclusive, in the sense of excluding people they perceive to be outsiders. The experience is very different in major cities, which is isolating in a different sense.
Do your children do a particular sports activity where you could join the board of a Verein or help out with catering? Or an activity for you - I go to yoga once a week (which is great for developing your German if you happen to want to learn the name of asanas), but we also get talking before or afterwards.
The one place I met loads of long-term friends was the local PEKIP group (the equivalent of NCT meetings, but all the babies are naked!) after my DC were born, so if you get pregnant, that might be one to bear in mind.
What happens if you invite kids round for a playdate? Could you get talking to their parents when they get picked up, and drop into the conversation that it would be nice to go to Film A, oh, do you think you'd be interested, should we go together? etc