Since you already have a few years of lifting behind you, you could really pack on some mass in the next few years. Your test levels are at their highest. Eat like a horse, train heavy with compound movements and you'd be suprised how much mass you can put on now. Then just wait, you'll be 5"11 and 250 when you start using gear.
I know it's tempting to start thinking about AAS use, but do some research in the next few years. Find out more about the different types of AAS, cycles, diet. Then when you're ready, you'll have the knowledge to start a good cycle. If you don't know what Anavar or Primo is, do some research, you'll be glad you did. The search button is a key to the mass of information on this board. Almost too much info!!!