sometimes you might ave to go to different stores for different products.
this. You mentioned Aldi, look into there if you haven't already, they're a forgetton cheaper in a lot of areas.
watch sales
stick with cheaper products, ex I eat a lot of chicken/turkey cuz it's cheaper than other meats.
Look into food shelves/SNAP. Even if you don't meet income requirements, they may be able to redirect you to other sources depending on what's available in your area. For example, there's a nonprofit in my area that buys in bulk from wholesalers, and has monthly sales, selling them in packages at a pretty good reduction in price compared to a grocery store, and it's available to anyone regardless of income