First of all,I am a self-taught golfer and I don't read up on anything and I never had a lesson so some of terminology might be different than you are used to,but anyways...

There are a few ways to get that proper in to out action on the hip,and to me,I try to keep it simple and think of everything as inside to out with all my body joints and I try to connect the joint and swing on the same plane as far as a rotational swing like yours..without boring you with twtoo's hypothesis on mathmatical and Physics way of the golf swing and all the nonsense only I understand and care about ,the basic joint you should focus on to check your hip flaws would be the tailbone..

if you are rotating on the proper path,you should feel your tailbone rotating and pivoting and very much stationary at least till the impact position...if come oustside in with your hip rotation,you will shift the tailbone.

another way to check up on this is to check your knees,if you do a proper hip turn,your knees will come together .Notice your first 2 swings there is more rotation of the knees than the 3rd one,and that is the result of the better hip turn than the first 2.Oh,try to maintain your knee flex on your right knee on the back swing.That will also help your hip turn and stick out your butt on the setup.



A drill I would try is to take your golf stance as you normally would with your left feet against a club stuck to the ground in front the left side .Take a swing as you normally would,if you are brushing against the club you are good with your hip.Looking at your swing,you are not going to be brushing the club and I would say you are going to miss is by a decent margin.That is what happen when you come across it with your hip turn..if you are hitting the club with some force and getting your hip past your left feet,that would not be a good thing either.Brush against that club and you are good..You can also practice against a wall without a club if you like..same difference.

Btw,I actually love the fact that your elbow is constantly attached to your core and it inhibits your arm from ending up in a higher position.I think it is a good thing.You might want to work on your flexibility a bit more and turn your shoulder and hip more to get the club higher and close to parallel and maintaining your knee flex,but there is nothing wrong with a flat swing.I say great majority of the average golfer would not be able to hit it with that short of an backswing,and I dare except the most expert of players to be able generate speed with that short of a backswing.There are plenty of good players trying to stay more connected and gain greater consistency by keeping their elbow attached to their chest.You are fortunate in that comes naturally to you.there are just fewer things that can go wrong when you do that.Don't think of it as doing something wrong,I would think of it as doing something right and try to build on that.

JMO.