If you are low in B12, all the iron in the world will not make it into new cells. B12 aids in the formation of the blood cells themselves.

I would ask for a B12 test, ASAP and bring your numbers and letters here. The lab ranges for B12 have not been changed to reflect new treatment guidelines. 400pg/ml is the new acceptable low. If you are below that then you may have neurological and finally anemia symptoms.

Iron needs acid to be absorbed. So take your iron with orange juice. If you take daily acid blocking drugs, you can be low in iron, zinc, magnesium, B12, folate, and calcium.

Since you recently had a child, I'd also take some fish oil to replace EFAs the baby took from you, and also have a Vit D test, to see if your Vit D is low as well.

Stop taking any vitamins 5 days before any further testing.
The ranges on the test results were not designed to reflect vitamin intakes from supplements. So false highs will report and you won't know your real readings.