The pointers from Elaine may be of help. Dietary iron beats supplemental iron any day:
If you insist on going with OTC supplements, I would suggest something like Advanced Ferro-Chel, which not only has iron in the correct form (chelated), but supplements the other components that may be deficient in your diet that help your body use that iron.
Have a steak. And some eggs. The iron chelated as hemoglobin is more readily transformed into human hemoglobin- unlike iron sulfate and other salts, which are poorly absorbed.
The iron in "Total" and other breakfast cereals is in the form of iron filings; you can show this with a beaker full of water on a magnetic stir plate. Throw in the cereal and a stir bar, and let it stir for an hour. When you pull it out, the stir bar will be loaded with steel "whiskers" from the iron, added to supplement the cereal. Guess how much of THAT is absorbed!