When I was 16, I was 6'5" and weighed 152 pounds. I was a tall skinny person. When I was 22, I got up 190 (all natural). Once I turned 25 my metabolism changed and I got up to 225 pounds.
Please wait until you are at least 25 to take anything. If you start now, you will seriously regret in the years to come. Your body is still developing naturally. Don't permanently screw up your body by starting now.
And tell your trainer to FUCK OFF. the fact that he is suggesting you start at 22 years old pisses me off. Also, the fact that he said to use d-bol as part of a PCT? That tells me, not only is if arrogant, but he a dumbass too.