Hi Leesee,
I’m sorry to hear that your Loom and Leaf isn’t working out for you so far, but you’ve only had it for a few weeks, so there may still be a period of adjustment for you. The good news is that you have 120 days to return it if it doesn’t work out for you. It may also be that at your BMI this product isn’t an appropriate “fit”, with the 4 lb convoluted memory foam in the uppermost layer and the polyfoam that is in the 1.5 lb range (see post #2 here). Quite often, low back pains can be a result of an item that does not provide enough deep support (see post #2 here).
Having a higher BMI presents special challenges and generally requires firmer materials (in the support layers especially). This could be firmer latex or innersprings (the type of support component would be a personal preference and in the right design either could be suitable) or even a zoned construction. The same overall guidelines apply with higher weights though that PPP (Posture and alignment, Pressure relief, and Personal preferences) along with using high quality durable materials that will maintain their feel and performance for longer periods of time are the way to make the best choices. Heavier people in general will need firmer and thicker comfort layers and firmer support layers than those who are lighter and because no materials will last as long with much higher weights the quality and durability of the materials and components is even more important than normal. I wouldn’t “rule out” any types of mattress and base your choices on your own personal testing. Post #3 here has more information and suggestions about heavier weights that is definitely worth reading.
I wouldn’t be able to predict which item might be a better fit for you, but both will offer higher density foams than your current mattress. There will be more options for customization and support core choices with the Luma Sleep, and latex will generally be the most durable padding material. I would trust the advice offered by Luma, as they are quite experienced with latex, and you’ll also have an option for more layers overall, which can be helpful with a higher BMI.
As you may be aware, both OSO and Luma Sleep are members of the site which means that I think very highly of them and that I believe that they compete well with the best in the industry in terms of their quality, value, service, knowledge, and transparency.
Phoenix