If you wanna get big you have to train big and eat big, simple as that.
Your upperbody isn't big enough than train your upperbody hard with weighted calisthenics, moves with harder leverage, weights if you have them.
After that eat a caloric surplus(only over by like 500 unless you want to get fat) and then presto magic muscles!!!!
"People think it's an obsession. A compulsion. As if there were an irresistible impulse to act. It's never been like that. I chose this life. I know what I'm doing. And on any given day, I could stop doing it. Today, however, isn't that day. And tomorrow won't be either."- Batman
He who makes a beast of himself gets rid of the pain of being a man.- Samuel Johnson