I really liked the song Amir!
As far as making it more "happy", I think you'd have to rework a lot - the tempo, the video, the recording - in order to make it more "happy" But if you wanted to do something easy to make it a little bit happier, I would try playing an E major instead of an E minor in the chorus. If you like that idea, you could also use an E mixolydian scale (E, F#, G#, A, B, C#, D, E) on the background/rhythm tracks and I think it would lose a little bit of that sadness that you were referring to.
I love that the bridge chords, the F maj to the E maj.
But I like the song as it is!
As everyone else said, that girl is gorgeous. :rolleyes: