All humans, male and female, have hair all over their bodies, with the exception of the palms of the hands and the soles of their feet. Aside from the hair on the head and the pubic region, most of this hair is relatively light and downy, and in many cases, it is barely visible unless viewed in the light from certain angles. On the other hand, a substantial number of individuals have thicker, coarser hair that grows on the back, arms, legs, and other parts of the body where it is not always seen as desirable.
For many men, most pubic hair grows in the area around the pubis bone. This is the area below your belly button above your penis. Pubic hairs on your penis shaft, foreskin, and even just below the head or glans are also possible.
You indicate that you are fully sexually developed in every other respect, which suggests to me that your light growth of facial hair is normal for you. When you say that you are fully developed sexually I assume you mean that your penis has grown, that your testicles have developed, that your height has increased, that your voice has broken due to enlargement of your larynx and that your body has generally assumed the proportions of an adult male. Hair growth is often the last change that occurs when the process of puberty is coming to an end.
I am 33 years old and was circumcised when I was young. Since then I have what I believe they call a skin bridge at the top of my penis. I find this a bit uncomfortable and unsightly.
Unwanted hair on the shaft of your penis can not only be unsightly, but can cause relationship or even health problems. Some partners may find hair in this area unattractive or even uncomfortable during intercourse. Excessive hair in this area can also cause certain health problems such as ingrown hairs or odor.
Now, parents have the option of finding out the biological gender of their baby long before birth. These two posts were specifically addressing issues of penis size in babies and have nothing to do with penis size during puberty. And even greater surprise when they started posting questions about their own penis size during puberty to the comments section.