Rajiv,
Fetal hemoglobin has a high affinity for oxygen, which means that it carries oxygen easily, but also does not let go of it as easily as it does with adult hemoglobin. However, it does supply oxygen throughout the body and is an acceptable substitute for HbA. You have to go by your son's energy levels and his growth pattern. If he is energetic and growing, transfusion should not be considered, as his Hb is still quite good.
I feel there is a problem here. Your son may be an excellent candidate for hydroxyurea treatment because he still has not transfused after a year. However, it is difficult to get doctors in the US to try hydroxyurea in thal patients. So, I would encourage that wheatgrass be given to the child in some form to see if it can help boost the Hb level. I would also suggest bringing up the subject of hydroxyurea with your doctor. Some doctors have had good results using a program of hydroxyurea and wheatgrass, especially with patients who have not required transfusions during their first year.