currently im 15 yr old sophmore
fastball 4 seam 80-83
2 seam 78-81
slider
changeup
i play for an organization at two levels the 16u and 18u
i noticed that at the 18U level I am much less tense and hit my spots and get outs much more efficiently. When i pitch for the 16 team. My mindset completley changes and my mechanics break down. I think im trying to do to much. Any advice?
Maybe you’re more focused against an older group of kids. So just think of the 16u league like the 18u league, just picture the same situation.
There was a series of posts dealing with playing beyond one’s level or age group, and after reading it again I came to the conclusion that you are apparently one of those people who do much better at the more advanced level. I think you should concentrate more on that one, as it seems to bring out the best of what you have and can do. 
thanks for advice guys
I think everyone at some time has had this problem. You play at the U18 level and pitch great, but then when you get down to kids your own age, you come down to level you think they’re at.
This happens to my HS volleyball all the time. Walk into a match overconfident because it might as well be a lock. All you need to do is show up. Then you play down to their level and they play up to yours. It’s one of the hardest things to work through mentally (plus losing to someone you’ve pegged as easy to defeat really sucks).
I’ve even had batters do this. It’s a good mentality for a batter to have sometimes, but I put a lot of thought into how I’m going to strike them out. Nothing beats having a chirpy batter sit down after two really slow changeups in the dirt (they usually make a comment at how bad you are here) followed by all you have right down the middle.