Anemia found on labs. Iron serum: 21 Iron Saturation: 4, Ferritin: 3. Very heavy periods, and hadn't been taking iron. Blood transfusion needed?

How do you FEEL? I'm glad this was recognized in time. You'll need a transfusion only if you're seriously symptomatic and can't last long enough to have your stores rebuilt by supplements. Please comply. Your best source of iron is red meat. Iron in spinach is bound to an acid that makes it not absorbable and broccoli as a wonderful source of iron is a myth made up by vegetarians. Good luck and be discerning.
Iron deficiency. It appears you have very low 'storage' iron -the ferritin. So if you supplement iron back, you should improve. Iron supplements are at CVS/drug stores. You should also get iron from foods. Broccoli, spinach, raisins, prunes, DARK chocolate, red meats, and some cereals like raisin bran or cream of wheat are full of iron. I doubt you need a transfusion unless your Hemoglobin is dangerously low.