Hi udoknowjac,
If the 100% natural Dunlop latex topper you purchased is 4.7 lb density then it would almost certainly be firmer than 16 - 18 ILD (it would more likely be in the mid/high 20’s) and given that Dunlop latex also feels firmer than Talalay in the same ILD range it’s not all that surprising that your topper is too firm for you. You can see some examples of approximate firmness levels and ILD’s for different densities of 100% natural Dunlop latex in post #2 here.
Unfortunately I can’t make any specific suggestions because you are the only one that can feel what you feel on a mattress/topper combination and there are too many unknowns, variables, and personal preferences involved for anyone to be able to predict or make a specific suggestion about which topper would be the best “match” for both you and the mattress you are using it on in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences) based on specs (either yours or a mattress) or “theory at a distance” that can possibly be more accurate than your own personal testing or sleeping experience (see mattress firmness/comfort levels in post #2 here). This would be particularly true when there are also more complex health issues involved. The specifics of the mattress under the topper can also make a significant difference in which topper will work best for any specific person since every layer and component in a mattress/topper combination will affect the feel and performance of every other layer and the “sleeping system” as a whole.
Having said that … wool has an amazing ability to help maintain a more neutral sleeping temperature (it can regulate temperature in both directions) and the humidity and the overall microclimate of a sleeping surface. Wool is also often a favorite material for many people that are more sensitive to pain (such as many people with fibromyalgia) because it can provide a more “relaxed” sleeping surface and can help with surface tension or shear forces on the sleeping surface (see post #18 here). There is also some evidence that it can help people reach the deeper and more restorative levels of sleep.
A topper can also reduce the amount of heat that reaches any memory foam underneath it or at least slow down the time it takes to become softer with your body heat which may lead to a combination of some additional surface softness and a different “feel” from the wool topper combined with firmer feeling memory foam layers underneath it. If you do go in this direction and you haven’t tried a wool topper then any return/exchange policy may become a more important part of your purchase just in case it doesn’t work out as well as you hoped for. While it may end up working well for you as it has for others (the only way to know this would be based on your actual experience) … you could also end up with a more temperature regulating sleeping surface that was still less pressure relieving than you hoped for.
There is more information about wool toppers and how they compare to various foam toppers (at least in very general terms) in post #8 here and in posts #3 and #6 here and there are some additional comments about wool toppers and a list of some of the better sources I’m aware of in post #3 here.
Phoenix