I think you mentioned earlier that your job involves Air Conditioning. It is not that different, you size systems according to load. Bigger pipes, bigger ducts, sort of similar.
The bigger the pipe the more heat that can be pumped through it. 1" pipe is fine for most normal residential loads, 1 1/2" pipe can transfer more than twice the heat assuming all other factors are equal. If it was intended to run this Boiler flat out all the time I would go to 2". My guess is that this would be an unusual install so 1 1/2" fittings is fine to heat what it was designed to heat.
A friend of mine has an old 20 room hotel, colder location, worse insulation, his Gas Boiler is about the same size as yours, hopefully that describes how grossly over sized your Boiler is.
A gas boiler can modulate, switch on and off, a gas boiler of that size in your house might only run for 5 minutes every hour.
With cord wood you can not turn it on and off, you have to compromise.
The default compromise you did last winter was to let the wood smoulder, produces less heat and lots of crap and the Boiler does not like it. None do, but this type especially does not like it.
We are where we are, so the issue is really what to do next.