Unfortunately, this sounds all too familiar to me :( I am 21/F, 5'6" and only 105 lbs. I am always FREEZING!!! I honestly think part of it does have to do with body fat (or a lack of in our case). But I also have kind of low blood pressure & I smoke (quitting January 1st) so obviously my circulation isn't what it could be. Do you know where your blood pressure normally hangs around? Because if it's low, it can definitely be causing you to feel cold. Feeling cold doesn't have to mean there's anything medically wrong with you though. All the women in my family are the same way, but are healthy otherwise. Do you smoke? Also, are you on any meds? That could also be a factor. I take Adderall (amphetamine) for ADHD and since I started the drug I've been feeling colder than normal. Well, good luck trying to stay warm and remember you are NOT ALONE!!!