Those are some colorful cleats
If you have a pitching coach I'd say stick with him. He can pay close attention to what you are doing and knows you, your arm and body a bunch more than we ever will. I think for your age you look strong, I'd like to see you throwing off of a mound to see how your timing is..It looks a little off in the grass here..but it's only 2 pitches. I would ask the coach if he thinks all you are going to do is relieve...why, because if you are a starter you will be asked to wind up...you need repeatable mechanics in the wind up also.
But I'd like to see more of what you have so bring it on..maybe someone else can catch something and help also.