I think everyone covered the DECA (only) CYCLE issue...so I won't say anything. I don't know if you should run any more cycles for a while. Just my opinion. Three things make me say this:
1. You are 19
2. You have anger management issues as it is...I'm concerned about you and others' around you.
3. I think Swole and chest6 tried to say this...you are only 160lbs and probably haven't even tried to gain weight through diet and working out alone. Sounds to me like a recipe for disaster. If your diet isn't right, and you haven't spent the time to get to know your body and what it responds to, then steroids aren't going to do much good. The same thing that happened before (gained a quick 20 and didn't do anything to maintain it...so you dropped it just as fast) will happen again. Do a little research, run a few diets and start a consistent workout routine. Once you have all that in line, you will have much more success with the cycles you run. Right now you are just wasting time and money. Time is money....you owe me $20
j/k

lighten up man, life's too short