Even if it isn't true about him thinking you are creepy, the message is clear: for now anyway, he's not interested, and rightly so. He's in high school and his friends (everyone actually) would think HE was creepy if he were seeing a 12 year old, especially when you aren't in the same school yet. They'd call him cradle robber and worse. When you are older, even a few years from now, 2 or 3 years difference is nothing. So try to pretend you don't have a crush and just say hi when you are at your friends and be as casual as you can without being fake. If that means staying away from him, then that's best.