Others on this site have a lot more experience with the youth game than I. But from where I sit, I've coached matured men who have come off shoulder and lumbar sprains and injuries with the same motion that you have displayed here.
It takes a lot of muscle coordination and fitness to pitch - at any age. It looks as though you have a bit more growing and maturing to do, muscle wise. All of this takes time. Don't rush things. Give yourself a chance to mature a bit more with your muscular development and you'll do fine.
By the way, I've coached several Asian men in my career, and I have found that they develop slightly different than their European, Canadian, Latino and American counterparts. These pitchers (Asian) ten to rely on finesse and pitch with a set of pitches that are used almost surgically. But then again, muscular development - strength and conditioning is the key to success with this sport and pitching. So give yourself time.