mommies of boys please help!!!

My three month old son keeps peeing out of the top of his diaper. I make sure to point his penis downward while changing his diaper. But it doesn't seem to matter. What am I doing wrong? His diapers are not full, they're the right size. I feel a little dumb for asking but we've changed clothes four times today! Sorry if you can't tell he's the first boy I've ever had experience with.