Like he said... A good boxer is a boxer with good strength, good endurance, good awareness and good speed. When you're in the ring, contending a world championship belt, then body type matters, until then, get control of the stuff you can control!

Good work with the body weight exercises, go easy on that wrist, skipping might be good as it'll build the forearm muscles, supporting the weakness better and give you a good card workout at the same time.

Shadow boxing is great, but without the technique to match, you're just dancing, and if I ever see people dancing like that, I know they're going home alone. Find a local gym to train with, if you're not feeling up to a full on boxing gym (because, actually they can be quite threatening places until you get used to it) look for a boxing based fitness class (boxercise?) To get the basics down and get used to punching a bag, be careful with bags though, its very easy to wreck your wrist, not so easy to heal!

Hope that helps a little? And yeah, you're body type sounds fine.