You're doing fine. You will probably hit a growth spurt in the next year or two and gain some more inches quickly.
It's normal to not have much armpit hair. It often doesn't come in until 15-16.
Your penis can grow into your early 20's. 4.8" is very close to average for an adult - a new study indicates that is 5.1".
You'll likely get some acne, not everyone does, and your face will become more "adult" looking over time.
Basically, changes take time. They don't all happen at once and everyone is different.
You appear to be developing normally.
Hope it helps.