How do i make my man feel better about himself

So me and my boyfriend have been dating for over a year now. Yes we have sex and everything like most couples do. But what I don't get is he knows he pleases me and makes me happy. But he thinks he's not and I fake everything because he's "small" I don't think he's small I've seen way smaller then what he is and honestly it's just frustrating me that he doesn't think he's pleasing me. What do I do to make him feel better about himself.?