Hi Dawn, Welcome to Healing Well we are so happy you found us here and hope you find this site informative and supportive for you .
I too have had a difficult time trying to get the breathing thing under control with my anxiety and panic attacks. My counselor has said just like vdaloka76 here mentioned that learning how to breath from your stomach and not your chest is big help with this. If you have ever watched a baby breath then you will see that their stomach rises and falls, not their chest. So, somewhere along the line as we grow into adults we adjust to breathing from the chest and end up taking in less oxygen. When you go into an A/P attack your O2 level is even more restricted as your heart is racing and your gasping for air, it is so difficult to concentrate on breathing at these times I know.
I have a few links on breathing techniques that I have practiced on and will post to you below. It isnt something that will help over night...at least it didnt for me but, if you keep at it you should be able to start to control some this I hope.
Also, exercise is wonderful for helping with anxiety I have found...whatever you can do and I listen to a lot of meditation music when I start to feel an anxiety attack coming on (I have my iPod loaded down with it) it has really helped calm my mind and nerves quite a bit. Just to add a few to what vdaloka listed for you. Take care and keep posting to let us know how your doing.
http://www.chinese-holistic-health-exercises.com/anxiety-breathing-techniques.html
http://panicdisorder.about.com/cs/shbreathing/ht/breatheproperly.htm