Hi healthysleep,
Welcome to the Mattress Forum! 
You are most welcome.
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GOTS and GOLS are certifications mostly concerned with the organic nature of products, while Oeko-Tex is a certification for VOCs and harmful substances in the materials used in the mattress (or the finished product as a whole).
Most people that are looking for an “organic” mattress or materials are usually concerned more with “safety” than whether the materials have an actual organic certification and they usually aren’t aware that an organic certification isn’t the same thing as a safety certification.
There is more information about the three different levels of organic certifications in post #2 here and some of the benefits of an organic certification in post #3 here.
There is more about the different types of organic and safety certifications such as Oeko-tex, Eco-Institut, Greenguard Gold, C2C, and CertiPUR-US in post #2 here and more about some of the differences between organic and safety certifications in post #2 here.
There are also some comments in post #42 here that can help you decide whether an organic certification is important to you for environmental, social, or personal reasons or whether a “safety” certification is enough.
The only reliable way to assess the “safety” of different materials in more general terms is based on lab tests and the certifications they have for harmful substances and VOCs (regardless of whether they are organic or natural or synthetic) so that you have some assurance than the VOCs are below the testing limits for the certification. If the materials in a mattress or the mattress itself has a reliable “safety” certification, then for most people they would certainly be “safe enough”, regardless of the type of material or the name of the manufacturer on the label.
All the latex you are likely to encounter (either Dunlop or Talalay that is made with either natural or synthetic rubber or a blend of both) will also have a reliable certification such as Oeko-Tex, Eco-Institut, Greenguard Gold or C2C, and based on actual testing I would consider any type or blend of latex (regardless of whether it is synthetic, natural, or blended) to be a very “safe” material in terms of harmful substances and VOC’s (offgassing). With latex the benefits of an organic certification can be exaggerated and in some cases can be a justification to charge much more for a mattress compared to other similar mattresses that would be just as suitable and just as safe but are in much lower budget ranges.
I’m sorry to hear about you multiple health issues. Because of that and your interest in trying something out in person, if you can let me know your zip code I can see if I am aware of any latex offerings in your area.
Usually when people refer to an “organic” mattress it is one that contains latex. Latex is a dense material, especially what is normally used in the base layers of the mattress, and as a more dense material (more mass per unit volume) it will be a heavier product. Many latex mattresses are made in split configurations with the foam layers inside of the mattress on the left and the right side using separate pieces, which makes it easier to transport and assemble and ship the mattress, and also allows for customization of comfort on each side of the mattress. If you do think that you will purchase adjustable bed bases in the future, you may wish to consider two twin extra long mattresses, as it will give each of you the ability to manage your sleeping positions independent of the other.
I think that the information I’ve presented here gives you a bit of reading and a good start about certifications, and based upon everything you’ve mentioned I’ll wait to learn of your zip code to see if you can test some items in person and then based upon your results with that I can expand upon more specific questions about materials, etc., or particular online companies or manufactures you might be considering (including the members here of the site, of whom I think very highly and I believe that they compete well with the best in the industry in terms of their quality, value, service, knowledge, and transparency, and they are extremely knowledgeable about organic certifications and latex and different configurations.).
Phoenix