Hi Ug,
You are not small. Average for a 14-15 year old is about 4-5" and average for an adult is 5 - 5 1/2" so you are almost there. One thing, you see your penis from a different angle than that of your friends. It can account for the difference.
Most variation comes when not erect. Some guys are "showers" (like "show") others are "growers." I doubt you see all these guys walking around erect.
In reality, it doesn't matter. Your penis is more than adequate to please a woman.
Not all 14 year olds have armpit hair. In many guys it doesn't come until 15 or even later. Don't compare yourself to others, we are all different and develop at different rates. You are unique and you are NORMAL.
Your penis can grow into your early 20's.
Hope it helps. Now get out there and BE CONFIDENT about yourself and find a girlfriend.