I just turned fifteen and have been taking lessons for a little more than a year. I would say while finding an NPA certified pitching coach is a good thing - it might be better to find someone a little closer to home.
I was in the same boat as you in the Spring of 07. I was a pretty good pitcher, but had never had any formal training - when I got to middle school the coach there didn’t allow any lessons so he tried to teach pitching in the end I went from a pitcher that could throw strikes to one that couldn’t hit the broadside of a barn - but that is another story. I didn’t make my high school team during the first tryout - I was the only middle school player that didn’t make the high school team. Talk about humbling. I made it in the Spring tryout after a bunch of work - this is recorded in the log. I wasn’t the go to guy at the beginning of the school season but was one of the go to guys by the end of summer ball. I’m not trying to brag but just want you to realize that frustration is part of getting better - when you are no longer frustrated with something you probably won’t keep practicing to get better.
Anyways - after my 8th grade year - my parents realized I needed help so they contacted some travel ball coaches regarding lessons. These coaches referred me to a guy that pitched in a D1 school and in the minors (AAA). I have been taking lessons from him ever since. I have a bunch of stuff that he has told me written in my logs - I do this so I can compare what I read from some of the folks around here. Read it, the log is very boring - but it serves it purpose.
I have grown to trust both my pitching coach and several folks on this board (DM, JD, Roger, Coach Ellis, Coach Baker, and the snake jazz guy) - because they almost always say the the same thing. I guess what I am saying is look around in your area - I am sure there is someone that can help you that is only fifteen minutes away. Also realize that it is a looong journey to get better - it has taken me over a year to get where I have command of just two pitches and an increase in velocity and I will continue to work to get better so I can command my change-up, curveball, and maybe my splitty. But don’t give up. Maybe some of the admins on this site can give you or your parents some questions to ask the perspective coach.
Maybe step away from the mechanics - for awhile - but work on arm strength and conditioning. Do - Long Toss & conditioning baseball is just a game it is supposed to be challenging and fun. It doesn’t sound like it is too fun for you right now. In the end stay focused and pitch like you pitch not like lincecum or maddux - it’ll pay off in the long run and the game will be fun. It will teach you things about yourself that you never realized. You may not be the stud on varsity or the D1 prospect - but you’ll know a whole lot about overcoming a challenge & I think that is what sports is really about.