Stove not heating room, please help a newbie!

I am hoping may be able to help with some issues i am having with my log burner.
I have a town and country little thurlow which was installed summer 2012. I had a good first year getting used to how it worked and enjoyed having my first wood stove.
Roll on to this winter, the fire wasn't burning right at all i had to have the top vents open all the time just to get the wood glowing.
I called in a chimney sweep who after eliminating damp wood etc and giving it a good sweep ( he commented that it was very clean) he could only say that i had an anti down draft cowl fitted which could possibly be the problem, he changed this for me for a standard cowl.
A couple of fires later and it was burning ok, a couple more and it is not coping very well. The wood i use is from a local wood merchant, i hae dried the wood on a radiator so it is bone dry! I can get the fire very hot with both top and bottom vent open, on closing the bottom vents the fire still burns and closing the top vent a bit results in the temp dropping and the flames disapearing, the other night smoke started coming out of the top vent. I have not used the fire for a few days and there is always a smell of smoke or charcoal. I dont feel that the fire is throwing out a great deal of heat, i seem to have to tend to the fire loads and struggle to have any flames.
Is there anybody ou there who has experienced similar or have any advice. My wife is giving me grief and rightly so, my one and only expensive demand for our new house is not being used and its cold outside
Many thanks to all who recommend anything