also what you could be doing is bottom turning to hard.this might happen if you're trying to basically go straight up and hitting it with you board flat on the face of the wave. dunno if that made sense. anyway try a more smooth style, like setting up earlier and not jerking it up at the last moment...
this might not even be the problem.so what helps is if you get someone to film you. then you see how k@k you really ride,haha happened to me

and like elementree said, bigger waves=speed=bigger airs
hope you come right dude