Hi alwayshopeful,
Welcome to the Mattress Forum! (better late than never)! 
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.
Since latex is one of the most popular topper materials there is more about the pros and cons of it in post #2 here.
There are guidelines for selecting a topper in post # 8 here.
Some sources for toppers of which I am aware are listed in post #4 here.
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. See post #4 here for some topper options of which I am aware that can be returned.
I hope that information is helpful to you.
Phoenix