If you haven't bloomed, weight lifting is just an activity. You don't have enough testosterone to get really big and strong, yet. Save the money for next year. Train with the school. Your goal should be to learn the lifts and start building a baseline of strength and work capacity.
If you are getting hair all over your body and are really growing, consider the baseball trainer. You may benefit from some more specific training. You may also benefit from someone pushing you personally with your own program.
I would probably still train at the school before moving to the personal trainer. Again, learn the lifts first and get stronger first so that you can really benefit from the personal trainer.
Either way, weight lifting is one of the safest sports around. Olympic lifts are safe and teach you explosive power. You aren't strong enough to hurt yourself unless you do it extremely wrong.