Hi KNR
Just kind of wondering if you have tryed any Cognitive Behavioral Therapy for your beathing problem, taking a big breath and yawning is the body's own way of trying to relax it's self, allowing the body more air in and helping with the hyperventilation buy breathing slower and deeper this should help with your anxiety as well.
Cowboy up
deep slow breathing is best
with the paper bag, you breathe in some of your carbon dioxied which calms you
hyperventilation is described on the net and is often a bad habit, associated with anxiety