Some points I wanted to make (please forgive the bullet form as i want to convey points of knowledge to you)
Tribulus is not sufficient for post cycle therapy, please read carefully the Post Cycle Therapy section under the Steroids category in this board, namely read about SERMs.
* Take a week off as a break. It's a bit like hitting the 'reset' button, you will see good gains when you start back up. No, you won't lose muscle gains either.
* Reevaluate your training program. There are tons on here, lots of good ones. If you lifted high rep low weight, lift low weight high rep etc. Change it up and keep your body guessing, that's what will make you grow. I bet you have done the same routine for a while?
* Natural test booster first, not steroids. At your age, your test level is probably diminishing a little (sad but true.) A good natural test booster like Powerfull will give you a kick to burn fat, build muscle ... maybe add a few lbs and keep the belly down.
* Add in some other things. Weight training is only a part of the equation. Add in jogging, sprinting, punching bag, plyometrics, stretching. Your routine must be balanced, the body must be exercised in the soft arts as well as the hard. Some of the biggest people I know practice yoga and tai chi! It's all about balance.
PS - Bulking unfortunately will add a belly, like it or not. Solution? Throw in some cardio, and cut every once in a while. It will give you renewed spirit to see all the muscle you've gained once you shed the fat on top.