Can it be dangerous if your ferittin is only 4 ml at age 19 and have had constant anemia for over a year? what could be causeing it all to be low?

Low iron: For some reason your iron stores are low - ferritin is the "iron warehouse" of the body. Either u are losing iron (heavy periods?) or not getting enough in your diet. Some vegetarians for example don't eat enough foods with iron in them. Certainly u need this problem to be solved because iron is essential for blood cell production and anemia is no fun. Hopefully your primary doc can figure it out.