Lately I've been extremely tired no matter if I get 8 hours of sleep or if I get 12 I always feel exhausted all day. I'm 18 not pregnant what is up?

See your doctor. You should have a check up. There are a lot of possible causes for being overly fatigued from hormonal problems (such as a thyroid disorder) to metabolic problems (like diabetes) or infections (such as chronic hepatitis or hiv). In addition, lifestyle problems could be at play - poor diet or excessive stress for example. See your doc, get checked, make a plan for wellness.