Hi Bamm98,
The experience you had the second night on the firmer configuration clearly reinforces your initial assessment that you would need more surface plushness / comfort cradle. If the 19 over 28 over coil was closer to your desired comfort but still gives you shoulder pains, the next logical step would be to add the softer layer of memory foam on top. This will help both with the shoulder pressure point issue and with getting the feel of memory foam that you like as opposed to the feel of latex that does not work well for you.
Unfortunately I still cannot pick up one of the options for you on an online forum as this is far too personal in nature and only you can feel what you feel on the mattress. If you want just a bit of plushness then the 2’ of memory foam would be a good choice, if you want more substantial plushness and pressure relief then the 3" would be the better choice. In either case you will not know for sure which one is the best until you purchase it and try it… the best you can do is to base your choice on your experience up to now.
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 the topper you choose also doesn’t turn out as well as you hoped for.
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.
Phoenix