If you're still too cold, a consideration is adding a natural latex topper. Similar to a synthetic memory foam (which tend to capture too much heat and off gas odour), the natural alternative is produced from the milky sap of the rubber tree. Naturally hypoallergenic and anti-microbial, the topper inhibits the growth of allergy-inducing bacteria, mildew, and dust mites, which is an added bonus to the comfort.
And if you want to go all the way, you can opt for a natural latex mattress, also made from renewable, biodegradable and sustainable materials. Platform bed owners, like ourselves, should note that these come in 6" thick version, without the need of a box spring, and come in "firm" and "medium firm" options.