My son is an 07 LHP. Roughly the same size too. It has been a learning experience. Start working on core strength and long toss. Start now. D1's want you at 85 for a LHP. They talk about movement but they judge by the gun. My son has curves that will just buckle batters but they don't care unless you are at 84-85 or above. They want you cruising at that speed too, not just touch it. They also will want you to maintain that speed through a few innings. They really don't care how fast you run either. If you start now you can get there without too much trouble. Showcases etc are pretty much a waste until you have the velocity. Lefties are rare so that helps you. I wouldn't worry too much. Just do long toss and get a good core strength program and your velocity should jump. Get the velocity then start showcases and email coaches where you will be pitching, attend camps etc.