There is a combination of things that have been said in here.
Wait till you are at 180 before you start to grab. I think you might be trying to grab too early which is causing you to throw your shoulders down or whatever which way.
Bring your feet to your hands. Although reaching for your grabs might look steezier, when learning them bring the ski to your hands: tuck your feet, point your toes, whatever it takes.
Try and just smooth it out! This was my biggest problem, I used to force the grab so much i would always feel off balance. But if you just go off the jump and don't exaggerate your pop or your reach for the grab it will feel much more normal! Just chill in the air and take things easy.