I found out I was slightly anemic over a month ago and my doctor put me on an over the counter iron supplement and it made a difference after a few hours, I'm 34 don't understand why age would make a difference in taking extra iron. If you don't want to take a supplement try eating a high iron diet. If you do decide to take an iron supplement take it at the opposite time of the day than your prenatal, your body will only absorb so much iron at a time.
I have always been anemic especially in my pregnancies. I was prescribed iron for my 1st pregnancy, and this (my 3rd) dr just asked if I have extra iron pills around I could take one or two of those each day. But like ThirdTimeA said, I just take one opposite my prenatal vitamin. She mentioned there could be extra bleeding at birth but not by much. She also recommended iron enriched foods like green veggies, special k cereal, eggs, meat... you can Google a list. I too am short of breath, weak, tired, so a healthy diet with iron and the suplements really helps. I cook asparagus in the oven with a little garlic butter and parmesan cheese and it's really good ;)