I'm freezing all the time, too! I don't have an explanation or advice, but I'm right with you, sister!
I'm also thin, fair skinned, with low cholesterol, and low blood pressure, too. I also don't eat red meat or poultry, just a little fish now and then.
I remember when I was a teenager and I ate everything, and was overweight, I was also always cold. This leads me to believe that for me, it's not diet related. I wonder if it could be a circulatory issue?