Hi JC9,
If your mattress is still in good condition and there are no soft spots, sagging, or impressions in the mattress … then a topper can be a good way to add some additional comfort or pressure relief.
If your mattress has soft spots or is sagging or there are impressions … then there are no great solutions but post #4 here has some suggestions that may be helpful.
While there are too many unknowns, variables, and preferences involved to use a specific formula or “theory at a distance” based on specs (either yours or the mattress you have) to recommend a topper with any certainty of success … post #2 here and the topper guidelines it links to can help you use your sleeping experience on your mattress as a reference point for choosing a topper that has the best chance of working well for you.
Outside of the topper sources that are linked there … post #21 here also has some of the better options I’m aware of that can ship throughout Canada and many of them sell toppers as well.
Phoenix