Kuddos to you for feeding your family top notch! You've gotten a lot of good ideas so far, and we do many of them ourselves. I've found that each CSA is very different, so you may want to try a different CSA next year and see what produce they provide to you. Some do half shares, which is nice if you want some veggies preselected and then you can add to it what works for your family. Hit the farmer's markets when in season, and consider doing your own garden like someone else mentioned. That is a huge money saver, if time is not an issue for you.
Definitely try to find a buying club -- we do ours through our local health food store. You can also buy cases of non-perishables from Whole Foods at a 10% discount (I think that's the % discount).
Try to incorporate more bean dishes to reduce meat, which is expensive when you are trying to only do high-quality meat/poultry. Once you master some bean dishes using the canned beans, then move on to use dry beans -- that's where the real savings comes in. Also buy grains in bulk -- brown rice, quinoa, oatmeal, etc. Rice and other whole grains are far cheaper than flour products with a meal -- and much better for you.
If your family eats lots of bread, invest in a bread maker and use that instead of buying loafs of bread. Making as much as you can from scratch is where real savings comes in, I think. If I had more time to make more from scratch I think I could save more money on our grocery bill (salad dressings, breads, tomato products). Someday! :)
Keep up the awesome work -- your family's bodies will thank you!