getting closer to another bday

So my birthday is next week and i have a problem...i'm getting old. I know that 28 isn't old but i feel old...my best friend...my brother is 7 1/2 years yonger than me and that makes me feel alot older. All my friends are younger than me and i don't know why. Is it that i am trying to hang on to being younger...they are good friends but than again they are like 6,7,8 years younger than me...and there is nothing wrong with that i just...sometimes i can't relate to them...i am a very private person and my friends are great...that is all i have time to say for now...i have to get ready to go to work... :(