feeling tired and very lethargic with little or no energy

Im a seventeen year old girl and for the past 5 months have been feeling so tired and very lethargic with little or no energy and more recentally i have been constantally cold with blue and freezing hands and feet and lips. However i still sweat alot. I bruise easily and play alot of soccor- while im playing i get so cold that it hurts. my pulse is 88bpm and my blood pressure is 85/65. i consume on average 1900 - 2000 calories a day and would drink about 4-5 litres of water. I have been at my doctor and have had tests done but im concerned as to what it is...any suggestions? Thanks