Larger stove, or Better Insulation?

Hey there fine folks of r/woodstoving

I have a Hearthstone phoenix from 2001 in my modestly sized home. I live in Northern New England and it struggles to keep the space warm on the coldest days. For reference, last night my thermometer outside read -3 but the stove struggles below 20 degrees as well.

Even with a fire absolutely ripping all day it was a struggle to even reach 60 degrees and I could not for the life of me get it higher.

When reading the manual, it says it should heat 1,500-2,000 square feet. My home is probably about 1,200 so I am thinking this has more to do with insulation and air sealing than the stove itself. We have a fat pointed at the stove from across the room as well.

Just looking for ideas or thoughts. I like the stove but obviously a newer stove designed for higher heat output/sq ft. is much cheaper than insulating and air sealing my 50+ year old home.