Joseph is right on. You'll definitely want to build the armor to fit your body, or else you take the chance of it looking wrong. Pieces won't fit just right (openings might be too big/small, strapping to long/short, etc) and you'll notice, especially next to a suit that fits right.
Also, AM armor is probably the best suit for your size. Send him a PM and get on that waiting list.
While you are waiting you can start sourcing the other parts, like tools, strapping, under suit, boots, etc.
Good luck!