I've had the mirena (levonorgestrel) coil fitted for the past 3 years now so i don't get periods but my iron levels are still very low 9.4 why?

Need to see a doctor: There are many causes of anemia (once it is ruled out that menstrual losses are the cause): and some can be serious. Bleeding in the intestinal tract; kidney disease; disorders of the red blood cells, or of the blood marrow, but anemia in a woman who does not menstruate really needs to be evaluated by a doctor to make sure nothing dangerous to your health is occurring.