Hi skyabove.
Welcome to our Mattress Forum. 
We’re “delighted” to have you here!
From what you’ve explained, you’ve certainly been on quite the mattress in-home testing and returning venture! It seems that you have higher than average sensitivities to any off-gassing and smell from these mattresses.
To borrow the bucket analogy from one of our Trusted Members, DIY Natural Mattress, if your “bucket” is already full of sensitivities that you do or don’t realize you have (gluten, corn, mold, environmental, etc.), then all it takes is one dusting of fresh pollen or the wrong foam (for you) in a mattress to tip that bucket over and give you very noticeable irritation and symptoms.
I’m glad you’ve found some useful resources here on The Mattress Underground! It’s very possible that these companies source products and foams that start off with a stronger odor. Sometimes even within the same supplier, there are noticeable differences in odor for different batches. Larger variations in odor tend to be found in natural Dunlop versus Talalay, but what odor there is tends to dissipate quite quickly.
There is more about the smell of latex in post #2 here but in most cases, it is reduced to levels below what people will notice in a few days to a few weeks but this can also depend on how acute your sense of smell is and on how sensitive you are to a particular smell. There is also more about the odor of new materials in post #3 here that may be helpful.
An option you may wish to explore is to look at a product from one of our Trusted Members: My Green Mattress. Their Dunlop latex tends to have less odor, and they source wool from a sheep in France that produces little to no odor! They use GOLS certified 100% natural Dunlop latex, as well as natural wool and GOTS certified cotton.
If you’re looking to steer clear of Dunlop all together, both natural and blended Talalay has a similar “sugar cookie” or “vanilla” type of smell, pass the same tests for VOC’s and off-gassing, and both seem to be well tolerated by those who are chemically sensitive.
Many (most, actually) of our Trusted Members will have NR (natural) and blended Talalay options available that you may be interested perusing. That said, I would generally suggest avoiding blended Talalay if you’re worried about flaring up any potential chemical sensitivities.
I would also recommend reaching out to any of them that you may be considering to let them know of your sensitivities, as well as your sleeping statistics, to see what they would recommend as your best fit.
Thanks for sharing your sleep stats with us! As you’ve potentially already read in our article on sleeping positions, side sleepers need comfort layers to be a little softer and/or thicker than back or stomach sleepers. At your 26.63 BMI, a good starting point for a good comfort layer for a side sleeper is 3" and then depending on weight, body shape, preferences, and the firmness of the support layers, to go up or down from there. Most side sleepers will fall in the range of from 2" - 4".
I hope I’ve given you enough information to move forward. If you come across a mattress or two that you are considering and would like some comments on, lets us know what that mattress is and density/layer construction specs, and we’ll be delighted to provide you a meaningful commentary.
Phoenix