Over the years, our team has been pretty small, but we're still pretty spirited. I think the reason for this is the fact that a couple of the older students go all out, kinda like you have been by being the mascot, but you've got to get a couple other people to back you up and be loud with you. Then the younger students follow. The reason this is is that no one really wants to look dumb or out of place, and if they see the "cool older" students cheering they will cheer. A good use of peer pressure!
Our team also have these flags that we like to wave at competition, that way we don't have to be extremely loud, but waving the flag still shows our presence and our spirit. So that's my recommendation is talk to a couple others and have them help you out, and just continue to have fun being the mascot! Best of luck!