Might be a silly thought, but, do you have the pipe sections aimed in the
right direction?
The lower pipe should enter inside the pipe above it to help with creosote
buildup and
air leaks.

That's backwards as far as my experience shows, and I've seen the same
woodstove set up both ways. The upper pipe should go inside the lower
so that condensing smoke (liquid creosote) continues to drip down
towards the stove firebox, and not out at the joints and onto the
floor. With a good draft, the direction shouldn't matter to the smoke
as the leaks shouldn't let smoke out but pull air into the pipe
instead, so the flow of creosote determines which way the flanges go.
If you need to control the smoke with the direction of the flanges,
then you don't have enough draft.

As far as the original poster goes, could you put an extension on the
chimney to get more height? Maybe your chimney needs a liner--a
chimney too large for your stove can cause as many draft issues as one
too small. Most chimney sweeps can install stainless liners in about
a day, or less. Also, consider a draft damper, like the oil furnaces
use. If you have enough draft except when you shut the stove way
down, it will allow enough airflow to pull the smoke along without it
having to go through the stove. I seem to recall it takes ten times
as much air for draft to move the smoke than you actually need to burn
the fuel, but I might be mis-remembering.

Are you using all the elbows to get nice vertical and horizontal runs
for your flue? Consider reducing the number of joints by running the
pipe at an angle instead. Most of the elbows can be adjusted to
smaller angles by rotating the sections, which might allow you to use
fewer elbows.

You also might have too much stove for your space--remember a
woodstove is basically a space heater, not a whole house heater. If
you have to turn it way down to stand being in the room, you're not
getting good combustion and making too much smoke. A smaller stove
might let you actually run it with enough air to burn clean and not
drive you out of the room. You can only move so much heat to other
rooms with fans and the like.

--Glenn Lyford