i'd say its either one of the three following things: ur diet isnt right, ur gear is bunk, or ur not training hard enough.
i know u said ur diet is good but a lot of times people think it is good when it actually isnt but from what u provided it seems to be good. im assumin u eat 5-7 times a day right? and plenty of water?
and im assuming u and ur friend use the same type of gear? but he's noticing gains and ur not so gear cant be bunk right?
do u train hard enough?
post some stats like height, weight, body fat....