Video your swing consistently from the proper angles, this way you can establish a baseline of your current swing and go from there, compare apples to apples. There are some great instructors here who might give you pro bono advice.
Start a swing thread, a journal will help you figure thing out.
There is a vast difference in the effectiveness of instructors and good ones are hard to find. Try and vet them as much as you can.
There are many reasons you could be shanking, my experience is that the more good pieces you put in your swing, the better your sequencing, the less you will worry about them.