Answer: Your body motion overall, mechanics as you call it, looks to me like you're trying to perform the best you can with what you know up to this point. 4pie gave you a great response in addition to his visual narrations. That narration I've posted below.
"It is not about throwing sidearm, its about having the good arm action. Once you learn to pitch with the proper arm action, you can start playing with your arm angle."
In addition, Pitcher17 followed up, again, with another great post.
I admire you willingness to learn, to seek out advice and to pursue this kind of sport - especially the pitcher's position. And as you notice, a lot of those that responded to your question are really there to help you - BUT, I seriously advise you to wait for your pitching coach before actually going to town with this stuff.
Why am I advising you of this?
I will freely admit that I'm more of a managing coach with a pitching staff and not that comfortable with "mechanics" as you call it. Therefore, I have seen countless of potentially good pitchers, waste themselves with "I'm gonna do it my way, on my own and figure this out," only to hurt themselves trying to do something that is beyond reason.
So, here is my professional advice to you:
I see a young man who could really benefit from a coach that knows what he's doing, and start you off on the right foot. Your desire to be willing to put yourself in the center of an infield, a place that not too many want to be. It takes shear guts to do what you want to do... I mean guts. You'll be criticized by those who know nothing about this game, and you'll get the blame for other's mistakes. But that's the way it is. That's why few really want to pitch. My hat's off to you for going this route. So...... go it right from the start. WAIT FOR YOUR COACH. 4pie gives some great advice on this site because he's been there and would never steer you wrong. Also, Roger has excellent insight into youth pitching and is NPA training and certifications can go a long way with you progress. So look, if you want to get this and get it right, do the smart thing and prep yourself for you pitching coach. You'll be glad you did.