Hi Cheergirl,
Welcome to the forum. You sound like a very nice person. But going through a lot right now. You are accomplishing a lot for age 13. I was totally different at that age.
The best advice that I can give you is to take life one day at a time and to just do the best that you can. You are practically raising your little brother. And I have a feeling that you just do things and don't complain much. You are intelligent and very kind for your age. You are taking over and helping your mom, you should be proud of yourself. I am proud of you and I don't even know you. I am glad that you help so much at home. I know it is hard but it will be worth it. When your mom finishes what she is doing, things will turn around and be easier for you.
There are a few sites for teens that I am going to post for you that could help you out. Otherwise I would talk to a school counselor if you are feeling too much pressure. Life itself is not easy. You are learning a lot right now which will benifit you in the future.
http://www.teencentral.net/
http://nineline.org/
http://forums.teenhelp.org/
http://www.teenhut.net/
I hope that these sites will help you. You sound like a really nice person, and I hope things get a little easier for you. But you do have a lot of wonderful goals. Talking to a school counselor will help you to cope. Maybe you might have to cut back on some things, but the more that you do, the stronger that you get.
Best wishes to you.
Hugs, Karen