I have been going to WinCo in Marysville (there is also another one in Federal Way). I have 2 VERY FRUGAL friends, and they told me about WinCo for a few years before I finally went there. And I'm kicking myself now for no listening. I live down the street from an Albertsons to get a couple of things, but my majority of grocery shopping is done at WinCo-their prices are the best. I also get a few things at Costco (cheese, eggs,frozen chicken breasts, those things are still cheap there).
I also do meal planning. I go through my cookbooks and recipes, I discuss what my husband might want to have (he always has an opinion). I buy only the ingredients for what I'm making, and then some other things too (yogurt, cereal, flour, misc items). I will buy meat at Costco, and then I Seal-A-Meal (vaccum sealer) the meat so it doesn't get freezer burned. It's a big investment, but before I bought it, I was wasting our money on other freezer bags, and our meat got freezer burned. I also think of things that I can make something else out of. If I bake a whole roasted Chicken, when there are left overs, I will boil it down to make 1 of 3 different Chicken soups. I will also throw in a couple of frozen chicken breasts (boneless-skinless) in the pot when I'm boiling the chicken, so I have more meat in the soup. It's also a good idea to make a 9 X 13 pan of things like lasagna & casseroles. You can take those left overs, and freeze them in plastic containers, so if you don't feel like cooking, you can just grab something from the freezer. I also make spagetti sauce from scratch. I make a big pot of it, and make lasagna, and then freeze the rest-when you let the sauce cool, you can put the sauce into Ziplock FREEZER bags. I say FREEZER because I learned from experiance, that the freezer bags are stronger and thicker than the STORAGE bags.
Coupons, I have found the best source is your local Sunday paper. If you live near or around Seattle, The Seattle Times Sunday paper is the best source for coupons. But, coupons only work on things you buy now. Vendors are big on promoting new items with coupons. I will cut the coupon out, IF I use the product already.
I have found when I stick to the meal plans, freeze the left overs, buy some frozen veggies-my dollar really stretches. I have been pleasantly suprised when my month is over, I still have meat in the freezer, and other ingredients left over. I over predict and sometimes over buy, but when I take inventory of what I need to buy for the next time, I won't have to spend so much.
I know you are buying diapers, and the cheapest source is Costco for diapers.
Also, another thing I did to save us money on baby clothes-I shopped the second hand stores, baby consignment, Goodwill, and Value Village. Babies grow super fast, and baby clothes don't wear out as fast as older kid clothes do. I always shopped consignment first when buying baby clothes. I did it with my 6 year old up until he grew into a 3T-4T. You can also find some great deals on toys, and other baby equipment.
I H. this has helped! Good Luck!