The more you use your penis the more it will grow. You have to exercise it by doing one of these things:
-masturbation
-sex
-pull it until it feels longer
-recieving oral sex
-putting a cream on it

if any of these natural things do not give you the results you desire then try using a male enhancement to enlarge your genitalia.

hi thanks,
i do masturbate, but its just soo small i can get an erction and it goes big enough, but just goes back small again.

what is oral sex? sorry

You are 18 and you do not know what oral sex is??
Ok, so oral means mouth...put it together.
Blow job.
So it is "big enough" when you have an erection. That's all that counts. Many men have very small ones while soft. There are ways to rock a small one in the bedroom anyway. Just gotta try different positions. I read it in Cosmo.
You'll be alright, no worries.
Good luck!

Yes you should be fine, but if you're too worried you can always try the natural penis exercises to help it get bigger.

You can sent me a private message if you want further details.