Is he interested?

Given the information, and assuming he really did want to go to prom with you, I'd say he likes you. Hands down. He likes you. But, the only way to know for sure is to try hanging out with him. Ask him to dinner, a movie, to hang out, play video games, walk in the park, and if you can start doing that, it'll be pretty clear his feelings.

He's a shy guy so don't expect him to take the initiative.

i think he does because he's giving you all the signs he does. but if he just smiles and doesn't say anything when your alone. it means he's reallllyyyyy shy and afraid to say something stupid. try to loosen him up a lil bit, hang out with him more and more and maybe he will loosen up on his own. give it time

good luck =]