Is it possible to only have a growth deficiency in the penis area, more specifically the testes and penis? I'm 15 now and I'm going through puberty very well except for the genitals. The thing is my testes are still small and I don't think they have even dropped yet, but I have pubic hair and hair in my backside. Also my penis hasn't grown. It is still like a baby. Will taking testosterone affect that situation?
There is an inherited condition known as "micro-penis" that is mostly found among those of Asian descent. It is described as a person who has a penis that is less than one and a half inches in length. The small size is not due to a lack of hormones. It is a genetic trait, such as having curly hair or dark skin.
Since you have pubic hair and the beginnings of body hair, it sounds like you have sufficient testosterone in your body. These things would not be happening if you lacked testosterone. Taking testosterone would be dangerous while you are going through adolescence. Your body has regulators to keep hormones at a proper level. If your testosterone level goes too high because you are taking it, your body will respond by shutting down your normal production. Since you are developing, there is a strong chance that that shutdown would become permanent -- not a good thing for a male.
Try out the Tanner Stage Calculator for Boys to see in what stage of development you are. It measures a number of criteria, not just the genitals. I suspect from your description that you are in stage 2. If so, your genitals will become larger over the next six months to a year.