Haha, ok man. Clearly, you must be able to squat and deadlift tons of weight. Go do some research on specific adaptation...
I'm still skeptical. 15 lbs of pure, lean muscle gain in 6-7 months is virtually impossible drug-free, unless you are 16-18 years old, in the prime of puberty and have raging testosterone levels and are experiencing "noob" gains. Something like 4-6 pounds of lean muscle gain per year is about the maximum possible drug-free for a lifter past the noob gain phase.
What is deadlift? Are you talking about strenght, or specific exercise?
Here is a recommendation. Jump in a swimming pool. Have two guys your size jump on your back, you need to keep head and both hands above water. Then swim few times across the pool. Then start over for an hour. Keep in mind that average waterpolo player is 190cm/100kg. That's waterpolo. ;-)
I wish you dont have to show your "strenght" to pro player.