Join the club! I came home when I was expecting second child and didn't prepare a budget. You're already ahead of the game. One reason to come home is that you spend more because you have less time to prepare meals. You spend more in daycare and buying double sets of things to take to daycare, as well as impromptu fieldtrips and/or late fees. You spend more to getaway to rest, and you eat more to burn off the stress. Not sure of your profession, but you eliminate drycleaning and weekly hair salon visits by coming home, also. Add two children to the equation, and for some professionals, you only work to pay everyone else to take care of the children and/or your home. That said, it probably helped that I didn't look at the budget because I might have continued working!
Anyway, you're right, food is still the biggest line item in our budget and I manage to blow that every month. But, what does help, when I remember to do it, is to create a weekly menu. It's tedious and doesn't allow much room for when you want to be spontaneous, deal with emergencies, or just cater to whatever taste you have that day, but when I follow my menu, I cut the grocery bill in half that week. I also manage to avoid impulse spending when I send my husband with a list. He might pick up a few odds and ends not on the list, but he's not nearly as bad as I am with that. I get caught by sale items and think, "oh, I know we'll need that," and "oh, we're out of that."
But, the average weekly grocery bill for a family of 2 1/2 who are omnivores is roughly $150, especially if you want fresh fruits and vegetables and you have a toddler/preschooler. Everyone in my house now eats, and when you have a preteen and husband, you can forget about a budget under $150 a week. Men and growing children eat around the clock, and if you want to give them healthy choices, you'll find yourself buying fruits and vegetables almost every two-three days. I know one family with five children, and the mom bought a food hydrater to make her own fruit and veggie snacks. I'm sure that helps, and saw one on sale at Sears for $30. I just don't care for the taste of dried apples or banana chips enough to buy them. She also makes her own ice cream, which I did enjoy and found to be cheaper than buying Breyers, unless you catch the buy one get one free sale.
Anyway, families of 4 who have managed to come under the $150-160/week have at least one vegetarian in the family, so you're buying smaller quantities of meat, and even then, it's pretty much just ground chicken, fish or ground turkey. Including two days of lighter dishes, like a salad and soup night or a dish with vegan crumbles instead of ground beef for the adults does help. Buying large bags of frozen vegetables also helps, if you have an upright freezer and cutting out processed fruit juices and sodas unless they are on sale. I read that you shop organically. You might have to research those fruits and vegetables that can be bought and it does not matter if they are organic or not. I read somewhere that you waste money buying some organic fruits and veggies because the pesticides never get inside the skin the way they are grown? Like bananas, for instance. And, buying that special spray for fruits and veggies might help you save some money while providing nutritious meals for your family. I notice a big difference in my grocery bill when I shop at an organic market and farmers' market versus retail store. That said, you'll have to determine what is best. Organic eating, sadly, did run our grocery bill to about $750+ for the month for a family of 4.
Ugh! Now, your children are still very young, so you can save on food items, but you still spend on diapers, wipes, and special soaps, etc. It might help to buy those items in bulk at a place like BJs which allows outside coupons and has its own coupons, or creating a mini co-op with another family that has two babies and split those bulk purchases in half. If you need clothes, make sure you trade with families through your church or your family network. That will save you hundreds of dollars per year. As for eating out, plan those days and try to stick to it. My family still eats out, but not nearly as often as when I worked out of the home, because I have more time to prepare meals. We instituted a pizza/movie Friday night and we use coupons for the pizza or make a pizza from scratch (my favorite as I can squeeze in some spinach and squash puree into the sauce in advance).