Hi Hammie.
Welcome back to our forum and thanks for your update.
I am glad that you are still sleeping well and that you are happy with your choice 
It is great that you’re gradually able to transition from stomach to side sleeping as you mentioned. As you may be aware, stomach sleeping is the worst posture for your lumbar region, regardless of core strength. Those that don’t have a firm enough sleeping surface to keep them in good alignment could end up in a hyperextended swayback position that can cause back issues. You combination sleeping could be a bit more difficult to deal with (than when you slept prone only) since the different positions have different basic requirements. Since most of us fall in this group, it is important to choose a topper that does not subtract from the support and firmness you need when sleeping prone but that adds enough comfort to address the shoulder pressure points you are currently experiencing when sleeping on your side.
I’d make sure that you chose a topper is not too thick as this will cause you to sink too much into a swayback position that might result in lower back pains. Depending on the percentage of time that you spend on your side, especially if you end up choosing a thicker topper you may wish to use a pillow or body pillow placed in front and/or behind you that can assist with “locking” you into the side position. Also, be sure to adjust the thickness of your pillow under your head when sleeping upon your side, as this often has to be a bit thicker than what you would have been using when sleeping upon your stomach.
You are correct, something using good “firm” support with some comfort materials on top that are adequate to allow for conformation of your hips and shoulders tends to work well for a combo side/prone sleeper. Shredded latex toppers can “displace” more than solid latex layers and provide pressure relief with less risk to alignment. If you chose to look into this option some sources for different versions of these I’m aware of include …
- CozyPure toppers and pads seethis post for more detailed information and feedback
- www.flobeds.com/products/linens/mattress-toppers.htm (has a zipper so the shredded latex can be added, removed, or zoned in different areas. See this post for more detailed information and feedback).
There is more information about choosing a topper in post #2 here and the topper guidelines it links to that can help guide you through selecting a new topper for your mattress.
Latex, in general, is the most breathable and “temperature neutral” of all the different types of foam materials but the firmness of a mattress and how much you sink into it can also affect sleeping temperature as well. A thin wool mattress topper also would have excellent characteristics in being temperature neutral. Additionally, there is more about the many variables that can affect the sleeping temperature of a mattress or sleeping system in post #2 here that can help you choose the types of materials and components that are most likely to keep you in a comfortable temperature range.
At a quick glance here are some of [url= https://mattressunderground.com/the-underground/our-trusted-members.html]our Trusted members[/url] that offer thinner latex topers,
Sleep EZ has 2" or 3" NR Talalay & Dunlop toppers
Arizona Premium 2" or 3" Talalay & Dunlop toppers
Foam Sweet Foam Has 3" toppers both Talalay and Dunlop
Latex Mattress Factory 2" or 3" toppers
My Green Mattress has a 1’ Dunlop topper
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.
I hope this helps and let me know if you have more questions and I or any of the Expert members of the site would be happy to asist you.
Phoenix