I saved up and bought a bench and some weights when I was 14 and all I did was sets of 10 reps on the bench and did an hour after school and an hour before bed for a year and a half, I never made it past 80lbs bench press and never gained an ounce, this presisted for a year and a half.
To start over I would do 5x5 on squats, deads, bench, overhead press and rows twice a week and eat plenty of good food and added weigt to the bar whenever possible. Would have been a far more productive start