This is as close as I can get it without clipping something else.

Note the settings I am using for the render.

                                                                       

This particular HDRI is problematic; the lighting's luminance might be causing unusual reflections on the shadow catcher. To offset that, I  decreased the Color adjustments Value to 0.6; it controls the brightness. I also decreased the Factor to fine-tune the render. 

My recommendation: get the model into its final position and pose; don't apply it after making the shadow-catcher adjustments.  Avoid making camera adjustments after setting the shadow catcher, otherwise you will wind up redoing the U- and V-Offsets. 

I got this render with a little trial & error, but I knew where to make the changes. But hopefully this should get you a little closer to what you want. It is still not perfect, but it is close.