It's not the size of the boat; it's the motion of the ocean...
I've spoken with many urologists on this topic and there is nothing you can physically do to make it larger (safely) - a penis pump will only work temporarily and is not recommended.
Let's get some facts straight first, the average penis size is 5 - 6 1/2 inches, so what are you really considering small?
If you are under the average, try not to stress out more about this, it absolutely is affecting your sex. Also, keep in mind, sex isn't just about penetration. There's oral sex as well as full body massage and touch.
Watch this video to get more information:
You can catch me on Twitter @jennatimetweets