Since you also have a dad, why isn't he stepping in to take care of ya'll? I know you're in your mom's custody, but especially since you can't legally drive, there are certain things you simply cannot do for yourself without one of your parents.

This is even more important for your 8 year old brother who hasn't had a mother for the past year.

I think it's Dad's responsibility as a biological parent active in your lives to talk to mom, or step in and live with you all or have you move in with him until mom can function again. I get that this must be insanely painful for everyone, but mom needs to push through that pain for the sake of the rest of her children who are still around who's lives could be affected by essentially losing their mother on top of a brother.

So sorry for your loss. Nothing can replace a meaningful person in your life; you eventually get more and more used to them not being there, but never stop missing them. It's an unfixable problem and one of the suckier aspects of life.