Hi Greg,
Thank you for your response! Sorry it has taken me so long to get back to you. The harmonic slurs are coming along ok, but are definitely still far from perfect. I think maybe I was a little unclear in my original post as to what is actually happening (or what I feel is happening) in my playing. It may not be a case of the teeth being to far apart but possibly that my lower lip is being pushed inward by the mouthpiece creating the feeling of a wide gap between the teeth. I hope that makes sense?
All the best,
Hayden