Update.
I got a new pair of AmFibs, in a medium. Although I was very nervous of trying them with my STI shifters since the time my original pair got stuck in the shifter, I have since used them twice, with no issues. These gloves are definitely for below 40. I wore them when it was between 30 and 38.
I also got a pair of Mavic Inferno gloves to solve the issue of what to wear when it's in the 40s. They are thin, but made out of some kind of wind block material, and perfect. These are men's gloves, but since Mavic is a French company, they run smaller. The smalls fit me perfectly. DH has been wearing them for years. I can also wear various liners, both wool and silk, as well as chemical heaters with both of these.
Problem solved.