It sounds like you are having a very hard time. Do you have someone to talk to ? A favorite teacher? School guidance counselor? Local pastor? I hope you have someone to talk to who knows how to keep their mouth shut.
You said that you can't stand up to your mom. You shake when you try to talk to her. I have a tough question to ask you. Have you been verbally or physically abused by her? I can't stand up to my step-father. I am afraid that people will yell at me if I screw up because of how he treated me at times. If that has nothing to do with it, don't think that I am saying that that has to be your problem. It is just one possiblity.
FEel free to ramble as much as you like. I know that I enjoy rambling on this forum. Don't feel that you have to answer my questions for us to read. It is just some thoughts. I hope things work out for you.