Ok, I am sixteen years old, and I am having a horrible time of it. My body is so confusing. I am about 5'6, yet I have about a 3.2 inch penis when erect and I have never produced sperm. I often attempt masturbation and I get some satisfying feeling, but I never experience ejaculation. Also, I some armpit hair in my right arm that is visible from a little bit away, while my other armpit is almost bald. I have never had a big growth spurt and my family members have hit their major spurts by now. I was a picky eater in the past and I hope that hasn't ruined my chance of growing normally. I need advice as to what I need to do to help me. Should I have a certain diet, or should I see a doctor to see if I have low hormones? Please help me. A simple response is all I ask.
I'll try to keep this response simple, but you raised several issues, so I want to make sure I cover most, if not all of your concerns.
From your description of yourself, it sounds like you are in stage 2 of development as Dr. Tanner described growth. See the description under "Stages of Development" for more details. On average, boys enter this stage around age 11.5 and reach the next stage in two years. At sixteen you're a bit behind the crowd, but not completely out of the range.
While the stages are divided into five divisions, you don't instantly jump from stage to stage. It is a transition that takes several months to several years. I put together a timing chart to show how long it typically takes to move from one noticeable event to another. So while your description puts you in stage 2, I can't tell from it whether you are near the end of stage 2 or perhaps at the beginning of stage 3. I would need to know a lot more details to pinpoint your development progress. To estimate what stage of development you are in, see the Tanner Stage Calculator for Boys.
There are two things doctors look for as concerns in late development: 1) has changes started before the age of sixteen, and 2) are the changes continuing. Here is where I don't have enough information to give you a good answer, since I don't know when you started and whether you have stalled. Doctors are concern if development stalls for five or more years.
Not eating well can delay puberty or slow down development. After all, the body needs fuel to change and if not enough is available, then it will have to slow down. However, in most developed countries it is extremely rare to find boys not getting enough to eat. Since you didn't mention your weight, I can't say even in general whether you are eating enough or not. What you should do, though, is concentrate on eating a variety of food, just as they say from the food pyramid. What I usually see is teenagers eating way too much fatty foods and foods with large amounts of sugar, and thus not getting a good variety of food in their diet. Even if you ate poorly in the past, your body will catch up once it gets adequate nutrition (within reason -- you still need to be in your adolescent period).
A penis size of three inches in stage 2 is typical, and actually suggests you are near the end of stage 2. Most of the growth of the penis in length occurs in stage 3 and the growth in circumference or width occurs in stage 4.
That your hair is not growing evenly under your arms is normal. Don't worry about it, the other side will catch up soon. There will also be times when you might notice that one testicle is bigger than the other for a short period of time, this too is normal.
I hope this helps. Let me know if you have more questions.
Besides seeing a doctor, how would I know if I have a hormone deficiency?
You wouldn't be developing at a normal rate for your age or in the normal age range. A person deficient in various growth hormones won't have a growth spurt, won't be growing body or facial hair, won't be producing semen, etc. Or, if they did experience some of these, it would develop at a very slow rate and you would be way behind everyone else. The only way to know if this is a problem is for blood tests to be done where the amounts of various hormones are then measured. Hormone deficiencies should only be treat by a doctor who would then monitor your response to the treatment to make sure the hormone levels are within the right range.
From your description of yourself, it doesn't sound as if you are deficient in any of the growth hormones. At fifteen, your development is normal or a shade earlier than average. I suspect you need to accept the fact that your "normal" includes having a smaller than average penis.