Look more towards your leading leg's postition at impact. Is it straight? Is there most of your weight on it at impact? Then, this will keep you in a good rotation and not slide. Where your back foot is will not be a concern...the heal it may be a little off the ground and that is a good sign. Does it HAVE to be off, no. But the leading leg cannot bend forward or still be flexed, if it is, you can expect you are sliding and not turning.

Do my wall/impact drill.