I know that in my household that food is the biggest expense and above our mortgage. We feed 4 and the OP has to feed 6. What I do and have done in the past is ...
- grow my own garden, store and dehydrate for winter,
- join a food bulk buying co-op (free and saves a couple hundred a month),
- we live in a rural area and can buy meat by the animal/ or half,
- shop at the discount grocer,
- buy seconds,
- bulk buy sales
- and just be aware of prices