I'm 12 years old and 5'9 so I am very scrawny and am looking for a tighter-fitting jersey, also 2 more questions: what is B and A type sizing?, is a custom-made jersey worth it if their is no size for me?
5'9 isnt it for M or L size. Anyway ask your dad to drive you to a Cycling / Sporting store so you can try them, i wouldn't buy clothing on the Internet unless you are completely sure of the size and brand that will fit you best.
problem solved: went to MEC and got a primal wear canada jersey for 50 bucks, (yes, I am Canadian) now I know what size I am, I'll likely start buying from love2pedal.com as aerotechdesigns.com had the most unattractive hard-to-use site