I'd need different ones for different phases of course!
For my childhood it would have been Harry Potter and the Order of the Phoenix although it's not my favourite movie at all, but the book is/was/has been. I think the bullying, standing out, standing up for yourself, the frustration, isolation, loneliness and self-hatred themes really do it. I still cry when I read that book, just because it's linked to so many things I suffered from as a child and sometimes still feel.
For adolescence, which I'm still in, I'd say Amélie and Donnie Darko.
Cheesy, right?