Welcome.
Not surprised your struggling, that stove is tiny for a house that size, even a well insulated one in a moderate climate. Im heating a house of similar vintage but smaller (1400) with a bigger stove (Encore) and still struggle getting the heat to the far rooms on really cold days.
You will get lots of help here for sure. You probably want to be looking at options in the 3 cu.ft.+ range for a house that size in New Hampshire (Think Woodstock Progress, Englander 30, Blaze King, Jotul 500, etc) But there are so many variables we can give you better suggestions with a bit more info:
- Do you have a budget range in mind?
- Are you hoping to heat 24/7 with the stove only, or supplement.
- Whats your idea of comfortable? 65F, 70F,roasting at a toasty 80?
- How is the existing chimney setup. Is there a steel liner in it and if so do you know the diameter and height?
- How is your firewood supply?
- Is a good flame show important or do you just want consistent heat? Is a long burn time between reloads important? (factors in the catalytic vs. non-catalytic decision)
- Do you have any preference on stove looks - ornate vs. functional? do you care about cast iron vs. steel vs. stone?
- Can you tell us a little about the layout of the house? Houses of this vintage tend to have a lot of small rooms which can be a challenge to heat evenly.
- How tight is the house? Have you had insulation upgrades, weatherstripping, air sealing etc done or is it uninsulated and drafty?
- Is the house located in a location that makes it unusually hard to heat - like on a hill exposed to wind, or heavily shaded so you get no sun.. ?
- I'm assuming its wood framed, but let us know if its stone or brick
Oh and one other thought - That small fireplace opening is going to be a challenge to fit a hearth mount stove any bigger into without modification. Are you open to modifying it as needed? Cutting into the brick above the lintel for a new pipe entrance would let you put a much larger capacity stove in, and then you might need to expand the hearth pad to meet clearances.