If your body is getting pushed up in the air away from the bike off jumps, it may be that your legs are too stiff - rigid - locked as you launch off the jump. What happens is that the suspension compresses into the face of the jump and then rebounds as you are taking off. If your legs are too stiff (or worse - knees locked) when the bike "springs up" then that upward force is transferred directly from the pegs to your 2x4 legs and it launches you.
One thing you can do is to "suck it up" - a BMX and mountain bike technique in which you start the jump with straight legs and then as you launch, you bend your legs and let the bike rebound up to you. You'll see this a lot at the pro level, when they are trying to stay low off the jumps - they can then straighten their legs and push the bike down to the ground sooner and get back on the throttle quicker. Another technique you can try is to squat as the bike compresses into the jump face, and then do a little jump with your legs as the bike launches (picture a skier taking off one of those huge jumps - just before he takes off from the big ski jump, he compresses and jumps into the air). Do this on SMALL jumps first to get the feel for it first. The best general advice is to stay loose. Too tight and the bike will toss you around. Hope this helps.