OP has glitter on her PV. True story. She's all kinda gily-girl.
As far as nose/mouth inhale-exhale, I guess it's just something some people have control over. I can have my mouth wide open and control my breathing through my nose. I can do it or not. Mostly, I exhale vapor through my mouth, only. I generally have to make a conscious effort to exhale vapor through both mouth and nose to taste the vapor. Sometimes I exhale through my nose, only. Any time I exhale through any other than my mouth, only, it's a minor thought process, whether conscious or not. When stealth, I hold and exhale through my nose, only.
I think, physiologically, the ability to close the nasal passage is controlled by the same diaphragm that "rattles" when one snores, and one's ability to harness it's function. If ya got it, ya got it. If ya ain't got it, you're bound to look like a dragon, even if it's a girly dragon with sparkly PVs and stuff hehe.