Began lifting, started with zero muscle, body shape looking a little better and bigger. Been doing SL 5X5 for 6 months, aggravated an old back problem I had, doctor's told me not to do any free weights which are too heavy on my back, such as squats, deadlifts, heavy barbell rows. Until I'm 21.

Since those were the core my workout, I'm feeling lost, just doing machine stuff like leg press feels tame.

Can I get big on another workout without those excersizes? Need some advice, plans and tips. I also want something that hits arms/shoulders just as hard as legs/back.

Current stats

Age: 16

Squat: 1xBW for 10 reps Deadlift: 1.5xBW for 10 reps Bench: 0.67xBW for 5 reps