Hi. Single mother of 2 teenage boys checking in. If you are in the US, I recommend getting a family lawyer and filing for both full custody (physical and legal) and child support. I'm not sure that any judge would emancipate your brother at age 14, or allow you to adopt a minor at 21 with no spouse. If a judge grants you full custody you will have a court order barring mom from taking your brother anywhere and you will still be eligible for child support. At the very least, you should file for emergency custody, which would allow you to keep your brother legally on a temporary basis until everything is sorted.

If your mom is seriously acting crazy, talk to someone about getting her an involuntary commitment for evaluation. If she gets committed, even temporarily, this will back up your case with the judge that your mom is an unfit parent.

At your income, I'm not sure that you will qualify for TANF, but you can probably get some food stamps.

Teenage boys eat a ridiculous amount of food. My best advice is to cook frugally. Get a crockpot and look up some recipes that will last you through the week. For example, in my house I make a whole lot of shredded chicken. Super easy, and you can freeze it. Today I had Chicken Korma. Tomorrow I will have bbq pulled chicken sandwiches. I also bake a lot. Cookies, muffins, stuff like that. I make them and freeze them. Learn how to shop sales and use coupons. I use a website called Living Rich With Coupons to help with this but there are tons out there.

Clothes and shoes are also crazy expensive with growing boys. You have to shop the sales and find coupons on retailmenot or whatever. I also get a lot of stuff for them at Buffalo Exchange, consignment/thrift stores, and occasionally those facebook yardsale pages.

Also, 14 years old is old enough to be looking for some type of work. Dog walking after school, yardwork, or something like that will get him some cash for whatever non essentials he wants.