You are struggling with one of the most common problems, with which the vast majority of golfers struggle. That is the "transition area" between swinging the club DOWN and DELIVERING the club through impact.
At the 3 o'clock position all you need do is rotate your hands, arms and club face back to square through impact. It's pretty simple. But raising the arms to the top is entirely different, because most golfers "open their arms, hands and club face" and now, need to swing DOWN, then deliver the club into the ball.
Getting comfortable in this "transition area" is tough. The arms and hands swing down before you can rotate and close the face of the club, thus everything goes right. Right?
There are 3 things you can do.
1. Begin trying to make 'EASY' 3/4 swings.
2. As your left hand comes down to approximately one foot before the ball, allow your left "pinky knuckle" to tuck and rotate your left thumb down and roll over to square the back of your left hand with the club face.
3. Assist your left hand rotation, by also rotating or rolling your right thumb down and through impact.
You may find you will start drawing the ball and thus need to swing out, across your target line.
The idea is to rotate everything around the butt of your club grip.
I do this and my typical 9-iron is 150, 7-iron is 175, 5-iron is 200 yds.