e gads mate... at your age you are on "natural" steroids, I would use this time to your benefit man, train hard and eat harder, it's what I am doing. I am coming up on my 20th in a bit here and I read over these boards and I see the gains that gear is giving people, but in reality for me, it is damn near close to the gains I am making without gear. Granted this is because I have a long way to go before I reach my true natural maximum as I have only been in the gym for a year whilst most of these guys have been doing it for much longer, but at 18 it would be hard to have reached your natural potential as well.
It is easy for you to believe that gear will give you massive gains quickly, but proper dieting and training at your age will do the same. If you think you eat hard, eat harder and if you think you train hard, go fucking nuts in the gym. Aside from that, Steroids WILL stunt your growth, simple fact and unless you truly believe your done growing I wouldn't risk it man.
If you have a hard time eating, throw in some cardio in the morning and throw down a couple BCAA's... guarantee you'll be starving for the rest of the day.
Last year around June I was about 5'9" 138 lbs 14% bodyfat, a small computer geek... Right now I am 5'9" 175 lbs 14 % bodyfat... I am huge compared to how I was before and I honestly believe that I picked the perfect time to get myself into the gym, when in your late teen years, your natural test levels are already off the charts, good stuff and it's free! I would do a lot more research before considering the dbol bro, just my .02 tho