Replying to Ski sizing help

Im 18 yrs old. Im an intermediate skier and tried starting freestyle skiing last year. Last year I bought line mastermind 177 with look px12 bindings and I have tecnica mega 6 ski boots. everytime I tried to do a box..... i would plan to do a 90 degrees turn onto it but everytime i tried poping up i would only turn 45 degrees.....it was very hard to pop in those skis......at first i thought i just cant do freestyle but then im guessing that the skis are tooo long.....in 6'2.5ft tall and weigh 140lbs.....average for my height is 170...any experienced freeskiers out there know what im talking about....should i sell my skis and get shorter ones or try to gain more weight or something?