I've al;ready had one person tell me "Your fanfic is a complete waste of time because fanfic is a complete waste of time". I've had people call me an idiot. In short, I have no self-confidence and am having trouble deciding if I should eve read exceprts at the bedtime Stories for fear of being jeered off the stage.
Sweetheart, every fic ever written is going to have at least someone look at it and think, "That story is a waste of time."
There are people who believe that fanfiction is useless, that anime is useless, that science fiction and fantasy are useless, that fiction in general is useless. They can all go boil their heads in a nice fish stew as far as I'm concerned. I love what I do, I enjoy writing--whether it be fanfic or original work--and in the end, what matters isn't whether I win or lose, or whose approval I win or lose, but how I play the game. It's cliche, but it's true.
In other words, enter the contests! Post online! Share your stories with the world, and ignore those who are close-minded and stuffy and tell you your hobby is dumb! And definitely bring your stuff to the bedtime stories; I'm in charge there, and if anyone starts jeering, I will have them ejected from the room. This is bedtime, not MST3K.
(However, don't ignore good constructive criticism. Too many people confuse "Fanfic Power!" for "My critically flawed fic is more precious than diamonds and above all criticism!" It takes time to learn to differentiate, but stick with it and strike a balance. Here's a clue, though; if their problem is with something (or things) specific in the story, it's probably concrit and good to listen to. If they're blindly bashing the story in general or making personal attacks on you yourself, they're a flamer. Ignore them.)