Learning Shorthand

I am 14 years old and have a teacher at my high school that was somehow talking about shorthand one day. I became extremely interested and asked her if she can show me a couple of things. After showing me some basic skills, I took one of her old textbooks. After reading somethings online, I realized she was teaching me Series 90. It would appear that this is not the best system to use. I really would like to use shorthand for taking notes in class because I believe I could write alot faster then the person sitting next to me. I am about at lesson 12 out of 70. Why do people not like Series 90? Should I try to switch versions because of speed issues, or would it be worse to have no teacher? If so, what version should I switch to?

(by monkeynoze for everyone)