Is the stove you installed rated to heat as much air space as you are heating?
I have a stove rated for 2000 square feet and it heats my entire 2000 square foot house just fine. I have a one story house and the stove is in the basement. I just have a small vent above the stove to let warm air rise up through and I leave the basement door open for warm air to come up that way also. I'm assuming since it is a log cabin you have vaulted ceilings so even if you have the same floor area as I do you would be heating alot more air than I am with 8' ceilings. Maybe you need a bigger stove.