Susan -
I'm not sure how much floor space your small Jotul requires (including setbacks), and thus what space you really have available, but a compact option which is not a
rocket stove, but which is a masonry heater, is Igor Kuznetsov's OIK-14:
http://eng.stove.ru/products/otopitelnyie_pechi_oik/oik_14
In his classification system "OIK" means a stove which is a space heater only (as opposed to stoves which also have cooktops, ovens, drying racks, fireplaces, heated benches,
water jackets, etc.).
To understand a bit more about Kuznetsov's philosophy and approach, it might be helpful to read his article "Advice for people building our stoves":
http://eng.stove.ru/stati/v_pomosch_lyudyam_delayuschim_nashi_pechi
Kuznetsov is a very well known Russian masonry stove designer and builder.
This is a double bell heater, and is the smallest floor plan brick stove of which I am aware. This stove is 2 bricks wide and 2 bricks deep in plan. For the larger Russian bricks, that would be about 18" square. It's not a lot larger than the typical brick J-tube riser. It is intended to be burned hot and clean, and then the draft closed after it tails out. For smaller American sized bricks, it would be about 16" square without any adjustments. It's about 1.8 meters tall ( a little less than 6 feet). As drawn, it will require approximately 180 red bricks.
By the plan, the exterior surface area (neglecting the top surface, which is typical)) is about 3.3 square meters, by my math. Assuming firing twice per day, the heating capacity would be about 1600 watts. If fired once per day, perhaps 60 percent of that, or 1kW, is a reasonable expectation.
A
video of a build of an OIK-14 by another stove builder (not Kuznetsov) can be seen here:
https://www.youtube.com/watch?v=DidZNcbNUHo
Here's an animation of a build (from yet another stove builder) for a version which has a firebrick lined firebox:
https://www.youtube.com/watch?v=pRgllRfazmY
If building this version, you'd need fewer red brick and some firebrick, but it would be much more durable.
I intend to build an OIK-14 as my first attempt at a masonry heater in a small gambrel roofed shed at our lake property (10x16 feet outside dimensions). This seems to be a fairly manageable first
project. I am still debating on whether I
should scale/upsize to match the original dimensions, or just stick with the given bond plan, using my smaller American sized salvaged red bricks.
Anyway, it's an option to consider for a small space, even if not a
rocket stove.
You could also build Kiko Denzer's stove hat on your existing Jotul:
https://www.handprintpress.com/wp-content/uploads/shopp/products/KikoHeaterHat-1.pdf
This would add thermal mass to your existing stove. Also not rockety, but another option.
Kevin