Grossness warning, skip this paragraph if you are not a dog owner. Dog food - the best way to see if it is nutrient-dense is to check out the poop. Is it huge? Then you are paying for a lot of indigestible material. Is it small? Then your dogs are digesting their food well (and you have less to pick up). Remember dogs are mostly carnivorous with a bit of plant material, they don't need roughage. Once you see which brands they are doing well on, then check cost per day per dog. I feed my 45 pound dog the grain free Costco dog food, and it is very cost effective. But I wouldn't get a Costco membership just for the dog food, Costco is a shopping accident waiting to happen.
Laundry - water temperature? Heating water is the main cost for washing clothes. If you can do cold water washes it will be much less expensive, unless your water costs are high. I think full loads (not overloaded ) are most efficient, since the agitator has to move no matter the size of the load, but if you have to do a small load, make sure your water level is lower to match. I find that if I soak a load of wash for several hours, even fairly dirty clothes come clean in cold water with a cold water detergent. Also, are you hanging your laundry or using a dryer? Line drying (inside in bad weather) is a huge savings. There was a laundry thread a while ago you could search for. If you find you run out of clothes before the last load on the line is dry and ready to wear, you could always buy more clothes - Charles Long wrote about that in one of his books (I think it was How to Survive Without a Salary: Learning How to Live the Conserver Lifestyle). Of course those were thrift store clothes, not brand new! I didn't find my laundry went up a huge amount once DD was in the picture - children's clothes are so small that it takes a lot to make a load, I just tossed them in with ours.
Re uniforms - I always had a school uniform and I had 5 blouses - my Mom did school laundry once a week (those 100% cotton blouses meant she had to iron them), and I was good for the week. I changed the instant I got home, before I did anything else, so school clothes didn't get played in and they stayed clean. Most schools have a "Fripperie" (sorry don't know the English word) where people sell the uniforms their children have grown out of. If your school doesn't have one, maybe you could start one? But your kids are 2 and 5 - school uniforms? That is kindergarten and not even anything. There are usually sports equipment exchanges at schools as well - skis, bikes, snowboards, skates, etc. - and if your school or community doesn't have one, again organizing one would be useful. This is nothing new, I grew up in an upper middle class suburb and these were standard. I wasn't a super athletic kid, so my parents didn't need to buy me top-of-the-line equipment, almost all my bikes and skis were second hand.
Sirius radio - why? Borrow podcasts from the library and listen to them. Or have the radio off and enjoy the silence. You are using your library lots, right?
Re overall expenses, someone on the forum (and I wish I could remember who it was so I could give credit) wrote that the easiest way to cut expenses was to cut and then cut again, until it hurt, and then go back up just one little bit to where it hadn't hurt, and stay there.