Your hands and arms move away from the body as you take it back; that is a disconnected takeaway. I would try to move my hands back straight or more to the inside--maybe feel like you're going to run your right hand into your right quad as you take it back. That is the feeling. However, the trick is to keep the club head outside of your hands. To do this, as you take your hands "in," feel the club stay "out" and hinge "up." It will feel like Furyk/Moore/Wolff, but you won't be any where near it. In reality, if you do it correctly, you'll look like Charley Hoffman and most guys who plane the club up the elbow plane. What you do is take the club back too flat. You gotta let that club hinge up.
It's not that you have a big turn; it's that you do it incorrectly. You let your front shoulder drop instead of keeping your level. Your shoulders should turn 90* to your spine. You turn too vertically and dip the left shoulder, losing your side tilt. Look at slo-mo video of new Tiger or 2000s Tiger--he moves off the ball a tiny bit and turns his shoulders behind the ball, but he doesn't dip the front shoulder or lose his side tilt away from the ball. You lean toward the target when you dip the shoulder; that causes you to jump because if you don't you'll sling the club over the top with that overly steep dipped shoulder.
Maybe. I wouldn't worry about that; I'd learn how to pivot correctly because even if you shorten your swing, it's no guarantee that you won't fall back into that bad habit. You're trying to cheat your way out of it by merely shortening your backswing--fix the root problem by turning your shoulders 90* to your spine and keep your side tilt; don't dive bomb that front shoulder.
Video reveals a multitude of sins. lol.
No. Your upper body should not be doing that at all. Your lower body, however, should squat, slide, and turn a little. The upper body just follows the lower body's lead. Think about a home run hitter; they plant that front foot and the chain begins. It'll feel weird but you should rig up a device or stand in the doorframe and take some swings, feeling your head stay back in the downswing while you unleash through the ball. Once you get that down you'll see a higher ball flight and hit the ball better.
You've got a lot of things to fix here, my friend, sorry to say. You have a lot of problems I had back in the day, it's funny actually. I don't envy you, but with diligent practice on the correct things, you can get through it and fix it. In sum here's what I would work on:
- Takeaway: hands "in", club "out" and hinged "up" so you can get the club planing back on the elbow plane.
- Backswing: turn your shoulders 90* to your spine--do not dive bomb your left shoulder. Take practice swings with a noodle next to your head or do them in a door frame.
- Downswing: kinda the same as the backswing. Keep the upper body back and let the lower body lead the way.
- If you get the body movements correct, you should find it easier to plane the club in the backswing, and then find it easier to match that same plane coming down. I would use the v1 app and a tripod to video your swing. Get that club going up the elbow plane and get it coming right back down it, and you'll pure it. See the attachments of good ol' Charley for the elbow plane. You don't get anywhere near the elbow plane as you push your hands out but suck the club in!
- Lastly, you need to grab a phone tripod and set it at about hip height and shoot the camera at your hands.
More years ago than I care to think about, I read an article by Trevino titled "Aim Left, Swing Right, Hit Straight". This sounds like what your instructor is wanting you to do. The ball should finish on your target line, or, as klineka said, where you WANT it to finish! Back when I played my best golf, my stance was square to the line, but I swung a bit inside out. The ball would start slightly to the right, and a baby draw would bring it right back to the line where my feet were pointing.
May buddy is another case in point, where the ball doesn't always go where the feet are pointing. He aims well to the right, throws the club OTT, squares the clubface at impact and pulls the ball into the fairway! Many times his Son and I have stood behind him to see him aiming into a grove of trees about 180 off the tee, only to smack one right down the middle!