Kim, maybe it is when you are taking the breath that is causing the problem. Watch your phrasing, when you need the extra power, etc. and watch closely when you breaht in and out, try to breath in just before, then let it out in a controlled way. Don't know if that makes sense or will help, but it works for me. It sounds as though you are holding your breath instead of letting the air out, which in turn can give you more volume.

Hope that helps,

kat