Kev,
first off, i'm a doctor, so maybe I can shed some insight into what's going on with you. Few questions first:
1) are you able to have erections and ejaculate?
2) as a child, were you on any medications for pituitary or renal/adrenal problems? Any childhood meds at all?
3) any current medications?
4) any history of genetic disorders in your family (e.G., turner's syndrome, trisomy 13, down's syndrome, kleinfelter's syndrome, etc.)?
5) how tall are your parents?
6) is your dad hairy/normal looking?
I'm 35 and I look like i'm 22. I shave about once a week, look very young, and get "carded" all the time when I am at bars, etc. No chest hair, no arm hair, and very little body hair. My voice isn't all that deep either. Some men just have low testosterone levels and never fully develop secondary sex characteristics. In your case, if it's not a genetic or medical condition, then I suspect it's just a combination of low testosterone coupled with simple genetics (i.E., short stature, slight build, etc.).
As for your penis, don't worry about it being small. As long as it works and works well, you should be able to please your partner and yourself without problems. Accept yourself for who you are and don't worry about what you think you should be. As you get older, you'll come to appreciate your youthful looks. It could be worse, you could be 22, hairy as hell, and balding.
My advice: if you don't have a family history of genetic disorders, you still might want to be examined by a physician. If you can, find a pediatric endocrinologist or regular endocrinologist and have a complete physical examination, including a complete blood work up (smac, cbc, testosterone levels, etc.). You could also seek consultation with a urologist to have your testicles examined to see if they are properly developed.
You're 22, which is still pretty young. Many guys don't stop growing and developing until 24 or 25. Each person is different in terms of growth and development. I would have a complete physical with labs to ensure everything is developing properly.
Zack