First a hug! *hugs*
I recognize all the things you're saying. I'm talking to this counselor (or something like that) now, and he helps me clear my head up. I'm just thinking to much. That's the problem with me. Maybe you're thinking to much too. And then I don't mean about maths or something. You think, you have to little time, for all the things you have to do. Are you sleeping well? When you get enough sleep, it's all easier. I don't sleep enough, so, there's a piece of my problem. Actually, I don't really know how to help you. I can just say, that you might go and search professional help, a counselor or something.