You can't get any more "mainstream and official" than the World Health Organization, which recommends:
"continued breastfeeding up to 2 years of age or beyond."
http://www.who.int/child-adolescent-..._exclusive.htm
As for the anemia, breatfeeding is the best thing you can do. While breastmilk contains less iron than formula, a much higher percentage is available to the baby's body because the breastmillk contains iron in the proper form to be absorbed.
To aid absorption of iron from the solid foods in Sarah's diet, consider giving vitamin C -rich foods at the same time as you give the suppliment.
"continued breastfeeding up to 2 years of age or beyond."
http://www.who.int/child-adolescent-..._exclusive.htm
As for the anemia, breatfeeding is the best thing you can do. While breastmilk contains less iron than formula, a much higher percentage is available to the baby's body because the breastmillk contains iron in the proper form to be absorbed.
To aid absorption of iron from the solid foods in Sarah's diet, consider giving vitamin C -rich foods at the same time as you give the suppliment.