I've got these gloves. I typically wear a large and after doing the FTP measurement verified that I need a large. I ordered a large and they are definitely mediums for size. My son has problems keeping his hands warm and he wears a medium so I gave them to him. He likes them for +30 temps (spring skiing usually) but anything below that and he says they are cold. Maybe the newer versions are better. View attachment 83804 He wears mitts with hand warmers now.
I've had 4 pairs of FTPs now... and I'm guessing, just from my own experience, that maybe you got the correct size but didn't wear them enough. They definitely start out very snug, and then after a couple of days fit, well, like a glove. I've also worn the exact gloves shown in temps down to -7F, and not had a problem. I have had cold hands with other gloves, so it's not just a matter of having warm hands - though I'm not as sensitive as some people.