Before you even march out onto the field take three slow, deep breaths, maybe even close your eyes while doing this. Then before each song...take one slow deep breath. Just relax, I'm assuming you know your stuff, just tell yourself I know what I'm doing, I'm ready. My DL instructer told my whole line to do the breathing thing....it gets you so relaxed. It's wonderful!!

You say your completely relaxed? Maybe you need to get nervous get some adrenaline going, then focus that adrenaline to just perform the crap out of your show. For those 8-10 minutes all you live for is doing the show, nothing else at all matters. ever. If you mess up no one is going to notice except you especially if you practice as much as you say you do, you're not going to mess up enough for anyone to notice.. Mainly you want to be nervous about doing good you don't want to be nervous about messing up. That sounds weird but their is a difference. Think about how awesome it feels after the show is done, try to feel like that the whole time.

Also what I think is important, is goofing off at the gate while you are waiting to go on. High fives, stuff like that, in my line our instructor comes around and shakes everyones hand and says do it up, and then we all just reachout out to whoever we can and click our sticks and say do it up. Im sure a lot of other people do it to, but it always just seems like that helps a lot. Kinda of a little joking between songs is good to, quietly and unoticeable to the audience of course. Just something like, "that was awesome" or something so just your line can hear it. Just kinda pumps everyone up.

Hope this helps.

PS I wish our schools stadium could hold 10,000 people!

That sounds reasonable, Thanks!
Yeah, our new stadium is awesome.

Glad to help.

Just have fun with what you are doing. Don't worry about what other people think of you because you are doing it for yourself because you love it. Yeah, mistakes happen sometimes but once its done, its done, theres nothing you can do about it. Just laugh it off and have fun with the rest of your performance.

And for me it always helps to get pumped up before a performance.

after 9 years of all kinds of performances (orchestral, band, full ensemble, small ensemble, solo) I find that I'm still worried about screwing up, even though I know that I've practiced as much as I possibly could.