C6-7 here...always cold like you unless it's 82 degrees but I always wear a cotton turtleneck shirt from LL Bean https://www.llbean.com/llb/shop/1816...csp=f&bc=12-26

I sleep with one on on and wear one from September to May. Of course I wear a flannel shirt or 3/4 zip sweater or sweatshirt on top of the turtleneck and I dress in layers. I crank up the heat in the house and also in my van. I would love to move to a more moderate climate.