On the vit D issue, I would like to mention that the McD diet does not provide any vit D, or so little. Therefore, Dr McD recommends plenty of sun exposure, to allow the skin to synthetize the necessary vit D. That may or may not be feasible, depending on where you live (Los Angeles vs Boston).
We are following the McD diet and are chonically vit D deficient, and we correct by using supplements. I aggree that supplements are probably not best, but deficiency is even worse, and we don't see much alternative, as the sun is virtually absent in the winter over here.
As was said, simple blood test can easily show if there's a deficiency.
Supplementing with iron looks to me as completely useless (the McD diet provides plenty of iron) and even dangerous (too much iron is linked to cancer).
Perhaps a B12 supplement would be advisable as well. Although, if you still breastfeed, your milk contains B12, provided you supplement, of course.