The first thing you should do is keep your receipts. Then go over them at home to see what your highest price items are. You might try to eliminate one or two of them a week. Or allow yourself 1 “treat” a week.
Many highly processed food cost a lot more than making them from scratch. However our work schedules are tight. Instead of buying a heat & eat item, maybe buy a bag of frozen mixed vegetables. Then if you have a supply of home cooked chicken pieces in the freezer & some pasta you can boil up quickly, you can put together a similar meal quickly. Sauces can be added from jarred sauces or you could learn a few quick recipes for sauces.
Watch your leftovers like a hawk. Freeze them if you can’t eat them right away. They become your fast food in the future.
Give these few things a try & aim to bring that grocery bill down.