Hmm...

I am not a doctor, but I know a bit about biology and physiology, so I might be able to give you a little information.

Leukopenia is a decrease in the number of leukocytes in the blood stream. It is the opposite of leukemia. A leukocyte is a white blood cell, and is part of the immune system. Leukocytes travel throughout the body and eat invading bacteria, in order to prevent an infection.

The cell count is measured in x10³/L, which means 10,000 cells per liter (of blood). The normal range is 4.5 - 11 x10³/L. A count of 1.8 - 2.5 is troublesome. It means that there are only 18,000 - 25,000 leukocytes in each liter of blood, when there should be at least 45,000.

You say that she suffered from anemia when she was a small child. Do you know if she still does?

The fact that she is short for her age and physically underdeveloped could definitely be explained by the fact that she was anemic, and suffers from frequent illness.

Like I said, I am not a doctor, but this sounds like a disorder of the bone marrow and/or the lymphoid tissue. Whether there was some birth defect with those tissues, or the problem was caused by some foreign agent, I couldn't possibly say. Medication that stimulates the production of white blood cells is probably a good idea, but it may not be addressing the root of the problem. She may eventually need bone marrow transplants, especially if the condition worsens.

Remember, my opinion is only that of a layman. I am not a licensed physician in any jurisdiction on Earth.

Stand and Be True,
Enigma