I'm 14 5 foot 8 and 165 pounds and 6 percent body fat are 15 inch arms considered big for my age?

No you are not considered big for your age anyway you shouldn't be comparing yourself to others because you should be happy with who you are and as long as you are happy with that, you should be confident and make the most out of your life

At that age and height, I'm thinking quite a bit. There are some men and women who look bigger with their height. It could be its body fat or a larger bone structure. This is the reason some would undergo medical surgery to enhance their body. With the popularity of going under the knife, the element of risk and cost of it has been reduced. Moreover, people who wanted to undergo cosmetic surgery wanted to feel and gain their confidence back. This is what I learned from lotusmedicalinternational.com