Hi Liv and welcome to the Mattress Underground 
Last time I bought a mattress, 17 years ago, I lay down on a couple, picked one, and it was perfect.
Now I am steeped in mattress research and fully overwhelmed.
First I went to mattress firm and picked a beautyrest that felt lovely, then I researched it and saw how the quality was called into question. Then I tried countless more mattresses and stores and found the same results. Either it was out of my price range ($1800 max) or it was in my price range and the reviews online werenāt great
Sorry to hear of your difficulties in finding a new mattress. Given your complex circumstances I understand why your journey to find something that meets your criteria is so difficult. Itās easy to get āanalysis paralysisā with all the information and also misinformation available! To start off, any mattress you finally choose will be unique to you and your husband based on your Stats (height, BMI, sleeping position(s) and any underlying health conditions) and your PPP (Posture and alignment, Pressure relief, and Personal preferences). So thanks for providing those details it certainly makes it easier to guide you.
One word about reviews, while they can be helpful in some ways, I would not give too much weight to them, as the reviewers all have their own Stats and PPP, and as well,ā¦some can just be thinly disguised marketing. I know you say youāve been āoverwhelmed with researchā, but if you havenāt yet I would suggest first reading The Mattress Shopping Tutorial to see how to find a good retail outlet and how to look for a suitable mattress.
and we picked the Brooklyn Aurora. Received the bed and I really dislike it. My husband can sleep on anything so he is totally fine but I feel like it has no support. The top layer is squishy, which I like (though I kind of prefer a quilted feeling) but then it feels like there is no support below it. Like I feel like we are hammocking in the bed, like itās sucking me in. Like we dip towards eachother. I really donāt like that.
Unfortunately, many of the mattresses you mentioned - Brooklyn bedding Aurora, Pembridge Luxury, Helix Dusk Luxe, and Midnight Luxe - all contain memory foam, gel foam and polyfoam of unknown densities and undisclosed composition. This can make it difficult for consumers to assess how these might support them as well as hold up over time. Keep in mind the Mattress Specifications You Need To Know and how they compare to the Mattress Durability Guidelines. I would make sure any foam in a potential mattress has no more than an inch or so of lower grade foam (for memory foam no lower than 4 lbs/cuft for normal range weights, and up to 5lbs/cuft for higher BMIs) and if polyfoam is used, with at least 1.8 lbs/cuft density, just to ensure you have adequate supportā¦I recommend caution if these specifications are not available. Memory foam of insufficient density can prematurely wear leaving divots or ridges which can affect both alignment and comfort (especially for higher BMI ranges and cronic health conditions) A high BMI presents special challenges and generally requires firmer materials (in the support layers especially). You may want to read a few guidelines for this here.
With a 13"+ mattress ā¦ the firmness would need to go up (than what you had for a less tick mattress) on average because thicker mattresses will āactā softer for most people. If you make changes to one of the specs (such as the layer thickness of the top layer) ā¦ then you may also need to make other changes to the other layers to compensate.
I went back to the online mattress store and tried the Nest Sparrow and liked it a lot though I am concerned that it sinks in a bit like the Brooklyn aurora. We tried the firm split bed. The reviews question Nest longevity too and their customer service. People seem to say that the quality and durability has gone downhill since they switched from the Alexander to the Sparrow
they confirmed that the slats on my Ikea bed are not sufficient and the warranty will be voided, even though this is the upgraded ikea slat system and Iām stuck with this bed for the next few years.
Nest Bedding, as one of the Trusted Members of the site, are very transparent in the materials and construction of their mattresses. The Nest Sparrow is a well-constructed 13.5" memory foam and polyfoam hybrid mattress, somewhat similar to the discontinued Alexander but with an 8" quantum edge pocket coil layer instead of foam for support, so similar to the other mattresses you considered. However, given that you are in the higher weight ranges the 3 comfort layers may not be that supportive and also may not hold up as well over time (0.5" 4 lb. Luxury Memory Foam + 3" 2.8 lb. Energex Cooling Comfort Layer + 1" 3 lb. SmartFlow Support Foam). The āsinkingā feeling may just mean you need a bit more primary support and enough secondary support in the comfort layer so that the foams are supporting the recessed areas of your body profile and keep your spine in neutral alignment.
I would keep away from the major brands for which you canāt find the mattress specs you need to know to assess how long any potential mattress is likely to last. You certainly do not want, In a couple of years, to start looking for a new mattress. So first Iād focus on durability and then on suitability. Because of the weight difference between you and your husband, and because the very different sleeping positions I would also consider to order a side by side split. Then Iād make sure that the mattress is customizable and if need be you can exchange or switch layers around.
I also would not buy anything that does not have some good return/exchange policies. I am assuming that you do not have another bed or can find another sleep arrangement for a while so I can understand your urgency. You have a short period of time, so Iād pick up the phone and call some of the trusted members and share with them your needs and explain your difficulties in going to test a mattress. These people are extremely qualified to help their customers with special needs or preferences.
Also, Biosleep Concept carries several foam and hybrid models, as does Magic Sleeper, Mattress To Go, Arizona Premium, and SleepEZ for example, and they have much more information on their components to help you make an informed choice.
I would be cautious using anything else but the recommended base for your mattress as you would not want to void the warranty. As your budget is limited to only buying a mattress the expert and trusted members can also advise you regarding the compatibility of your Ikea slatted bed frame; and modifications that can be made to make it suitable. Depending on weight restrictions, you may be able to place a Bunkie board or thin piece of plywood over the slats, as long as the mattress is not too heavy, and depending on the construction ā i.e., center support brace, additional legs for center support, and so on.
If at all possible Iād not give into a sense of urgency as that can lead to rush decisions!
~ Basilio