Sometimes wide hands is necessary with younger horses. They're like training wheels. It gives the horse more clear communication. They are very useful, but as he gets better to responding to your seat aids, start weaning him off them or else he will become dependent on them and only them for direction...hence heavy on forehand, mouthy horse.
As far as positon, your entire body is pitched forward a bit and it directly plays into how your horse moves. Look at the 6th picture and compare your forward slouched shoulders to his shoulders. You're both heavy on your forehands! You already know about your pinching knees. Get that lower leg forward and perpendicular to the ground and trot around in half seat until your thighs burn off your legs. It works great!
Pretty horse, but then I'm a sucker for TB's.