Hi maria98335,
Welcome to the Mattress Forum! 
I’m sorry to learn of your multiple health issues.
So it sounds like you have a newer mattress that provides you good deep support and alignment, but the surface comfort is too hard. You’ve previously tried a memory foam topper and a 2" 20-24 ILD Talalay latex topper. The Talalay topper didn’t provide you enough relief. While I can’t pick out a topper for you, as there are entirely too many personal variables involved in selecting something that is so subjective, I think I can provide you some good guidance on how to select a topper.
There is more information about choosing a topper in post #2 here and the topper guidelines it links to which along with a conversation with a reliable and knowledgeable supplier (that can provide you with good information about how their toppers compare to each other or to other toppers they are familiar with that are available on the market) can help you use your sleeping experience as a reference point and guideline to help you choose the type, thickness, and firmness for a topper that has the least possible risk and the best chance for success.
Because of the uncertainty involved with purchasing a topper where you can’t test the combination in person, a good exchange/return policy can also reduce the risk of an online topper purchase so I would also make sure you are comfortable with the options you have available after a purchase to exchange or return the topper and any costs involved just in case a topper you choose also doesn’t turn out as well as you hoped for.
Since latex and memory foam are the most popular topper materials there is more about the pros and cons of each of them in post #2 here.
There are also some topper guidelines in post #8 here that you can use along with your own experience on your mattress to choose the thickness and softness that has the best odds of working well for you.
Some of the sources for toppers of which I am aware are listed in post #4 here. If you are uncertain it would also be a good idea to check for any exchange or return policies just in case the topper you choose is firmer or softer than you would like (see post #4 here for some of the return or exchange policies of which I am aware).
With your first latex topper it may be that either the ILD was too plush for your personal preference (sinking through too much and feeling the firm mattress beneath), or that it wasn’t thick enough, so going to the 3" and just a little firmer (but still something that most would consider plush) could be a good solution. 3" for latex is generally a common thickness when people are expecting a decent amount of extra plushness, 2" for a smaller amount of extra plushness. And of course, what it is placed upon will also determine the “effectiveness” of the topper and the impact it will have.
This is a latex with slower recovery properties built into for people who specifically like the slower recovery characteristics of memory foam but want latex.
I hope that helps!
Phoenix