At 16 almost all supplements won't be liable until your 18.
You honestly just need to focus on your diet and training. Pounding calories. Whatever mom makes and go back for 2nds.
Take food with you at all times to make sure your getting adequate calories. PB&J's, nuts, trail mix, granola, rice cakes, banana's, drinking chocolate milk, drinking regular milk, orange juice, cereal's, bagels, english muffins, hard boiled eggs, beef jerkey, string cheese, yogurt packs.
The main reason a younger trainee usually slows down is
- inadequate calories
- trying to do too much
Stick to a VERY basic training program (Starting Strength, Madcow 5x5) or a very generic upper lower split (lyles generic bulking program).
KISS = Keep it simple stupid. Progressive overload, eating plenty of calories, and making sure food is the primary objective.
- Full Range of motion
- Proper Form
- Don't ego lift (Think you need to add weight to make progress).
The amount of change a supplement would make is so small its not even worthy of mentioning yet. You can't supplement a bad diet, so regardless of what you want to buy or get it won't help you if the calories are not there.
Post up a daily diet or what you eat, then add another 300-500 calories, and then come back in 2 weeks and talk about your lifts.