I think you are on the right track, but one thing I had to cut back on is music/sports lessons and I REALLY hate that.

Anyway, if you are focussed on having a big family then you can make it happen on a small budget. If you are focussed on having a new car every 2 years and new clothes every season you won't like it. It appears abundantly clear that you gonna have a huge tribe and you are going to love every minute of it!
There are some huge families on here with only one income, I'm sure they'll come in an chat!