Me being a self-conscious 18 year old, I have the same worries that you do. However, I am beginning to accept that I have an "average" penis as well. I know it is difficult sometimes to when feelingb inadequate because I used to compare myself with this website and porn stars (this being the Large penis support group). Being 18, Im sure you will grow more. I know im still in puberty because it dont even have facial hair, chest hair, thigh hair, or ball hair. So, your fine dude, relationships should be based off of emotional connections, and you should have no problem using your tool in bed either.