First of all I am sorry to hear that your hands and feet are always cold. To get the most accurate answer to your question, it would be best if you made an appointment to be evaluated by a physician. You are correct in questioning whether your circulation may have something to do with your extremities always being cold, as this is definitely in the differential as a possibility. In particular there is a problem called Raynaud's phenomenon where the individual is predisposed to developing vasospasms in the peripheral vessels of the arms and legs that can lead to cold, or even discolored extremities. More significant peripheral vessel disease (like arteriosclerosis) can also affect blood flow to the extremities. Without knowing your medical history, this would seem less likely however, because you are so young. There are numerous other possibilities for cold intolerance including metabolic disorders such as a low thyroid level (hypothyroidism). As far as improving your circulation, I would not recommend taking any medication to do so without first seeing a physician, however making sure that you are hydrated well, and exercising regularly will likely help. I recommend starting with your primary care physician
if you want to start a work-up. Best of luck.