Sounds like you've got the diet pretty well in hand. Pushups are a good body weight exercise, remember you can vary it though. Wide Arms, Diamonds, Clap push ups.... Also, don't get to caught up in just upper body, you'll need to condition you're whole body to be successful.
Squats, Pistols, Lunges and Mountain Climbers for the Legs.
V-ups, Crunches, Supermans, Situps, and the Supine bicycle for your core.
There's a lot of options out there to choose from for body weight exercises, check them out for yourself.
After that it's like Ramp36 said, you just train like heck and wait for the growth spurt.
"Remember when you are resting, someone somewhere is training, and when you meet him, he will win."