My weight is 65 kg. When there are 20 knots, and I'm fast with my 12 meters, I jump high, but I have trouble landing water, sometimes my body is twisted a bit while I have the kite in cenit waiting to drop a bit before moving the kite again.

Right before you're turning the bar to the opposite side in preparation to jump, go upwind with a quick, sharp turn. Once you're in the air, bend your knees instead of having your legs dangling in the air. lol