just try to vary your layups dont do the same thing all the time... but your young so you have a lot of time to get new moves down.. focus more on doing floaters or doing pullups till your comfortable with going up against bigger defenders. also the height of your jump and your hand placement affect weather or not its gunna get stuffed and always try to draw the contact.. even if it gets blocked you might have a chance to go to the line.

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Height:6'2
Standing Vertical Jump: 31.5"
Running Vetical Jump: 36.7"

Only The Strong Survive