I'm running my bottom blast with a recycled bathroom blower, rated at 115 cfm. It comes out of the blower at 4", reduces to 2" then goes 3" and up to the fire. I run it thru a dump valve just downstream of the blower- a blast gate on one leg of a 4" wye, providing back pressure to the other leg, to feed the fire. I haven't put any kind of meters on my system- I hold my hand over the firepot, feel the breeze and say "yup, thats fine". I usually choke the dump valve down halfway unless I want a lot of heat, choke it down completely and I get some major heat.
Does your setup work? Not work? Kinda work? It seems to be real complicated. Show us some pictures. I like to keep things simple and not over think things.
Steve