That is quite likely one of the dumbest thing a coach ever said....
Well, not true...
I heard a figure skating coach (the first athletes I worked with 17 years ago were figure skaters) tell a 13 years old girl that if she lost her extra 10lbs she would get her double Axel.
One college football player I trained was told by the new coaching staff that he would lose his starting job (linebacker) if he didn't gain 20lbs during the off-season.... now, he was already the strongest guy on the team and wasn't the fastest... adding 20lbs would have made him a worse player.
I jokingly told my player that we would train as usual, he would still be the strongest of the team and at the weight-in just put weight plates in his pockets.
That was a joke, but he actually did it... and it worked!!!
Anyway, of course this has no bearing on your situation.
You can't force strength gains. First your likely have long arms. So the bench press will be a constant battle for you.
Honestly how many 16 years old kid can bench press a true, solid form, no cheating 315lbs? 16 years old with long arms... with your body type it will take you some time to reach your strength potential on the bench press.
You remind me of one of my friends. at 16 we was almost exactly like you 6'2" and competed in powerlifting at 171.
He actually held the junior Canadian record on the deadlift with 535 (long arms = good leverage for the deadlift) but he could barely make 225.
He trained hard for years and eventually reached a 425lbs raw bench press and a 500lbs bench in competition (with a bench shirt). He also squatted and deadlifted in the 700s.
But by that time he was close to 300.
But the lesson here is that it took him about 10 years toi reach those levels, And he is a guy with a strong passion for training AND actually had very good genetics (his father was a national champion in Olympic lifting).
To reach a 315lbs bench from 225lbs took him about a year or maybe more.
So reaching it in 3 months is highly unlikely. I suspect that your coach only told you that to motivate you to get stronger. Because he obviously has no clue as to how fast strength can be gained, the effect of leverages on strength and how dangerous it can be to have a young guy try to go up to fast in strength.
If you are in this for your lifetime what does it matter how much you lift in 3 months? If a good college wrestler can bench 365 you have 5 years to get there. If you try to go up too fast you risk limiting how high you can go and might get injured in the process.