I am 16 years old and my penis hasn't started growing yet, but my balls have dropped into my scrotum and I can produce sperm. I have only gotten a few pubic hairs, barely noticeable leg hair, with no armpit or mustache hair. Is there a problem?
From your description you are somewhere in stage 2, which at age 16 is unusually late, but right on the edge of what is considered a typical range. Even so, I would suggest that you talk to your doctor about your late progress because it can be a sign of other problems. It also could be perfectly normal, but I would rather have your doctor confirm that.
Given that you have started so late, it also means you will finish late as well. Each stage lasts about two years. Since you are ejaculating by have almost no pubic hair, I would guess that you are at least half-way through stage 2.