$150 with 3 boys sounds like a good budget. You don't mention if you use coupons, but every bit helps. I don't have time to shop different stores to get the best bargain, but I use about $6 in coupons per month. Also Walmart will price match, but that is time consuming as well.
Do you use bar soap? Open the boxes and put them in the drawer outside their box. It will dry the bars out, they will last longer, and still work just as well.
Instead of Oxyclean detergent for stains, I found an old bar soap "Zote" it is pink and works just as good on stains and whites. You have to lather it up, but it is working in no time. The wrapper says it can be used on all your laundry (if you have the time). I find it at Walmart for under a $1, you can't beat that! Someone on here suggested only using half a dryer sheet. I tried and it works just fine! Clip them suckers in half! Do the same for the SOS pads, but quarter them, they only last for one use anyway. As well, cut the bathroom sponge in half. They always rip and you end up with two in the long run. There's at least $10 savings for a month right there.
If you can't save the money in groceries, save it elsewhere. I get car wash coupons from our water company. I save $3 on a $5 carwash. There's $6 for the month.
Do you have a smart phone? The app Dexknows will help you find the cheapest gas prices in your area. Use it.
I have learned to use a lot more scrap paper, rather than pulling out the note pad. I print coupons on the back of a used envelope. All I will do is clip it out anyway.
Use coupons to go out and eat. I usually plan our Sunday lunch or dinner right around what ever is offered. It works well enough for a simple lunch or dinner.
And be content with what is on sale. I went to the shoe store thinking boots would be on sale, I am well overdue. The cheapest pair in my size was $139.00. I had them in my hand, but walked around and found a cute pair of shoes for $29.00. They're not boots, but my feet are all shiny and I got something new.
Rather than purchasing a bottle of water on the road, get a water bottle. Only put water in it. That is most often what I do. I know for sure I previously bought a bottle every Sunday. There's another $5.16 for the month.
I also recently purchased cloth napkins for home. If they are good enough for a nice restaurant, then why not at home. I am not real strict on using them, but just think of how many times you just wrinkle a paper napkin...in the trash it goes.