Andy may be better able to inform you as to the severity of this mutation. Your son's thalassemia appears to behave like intermedia.
The two mutations your son has are exaclty the same.
While your son seems to be an intermedia, for optimal health, growth and development my advice would be to either attempt hydroxyurea or to maintain higher hemoglobin levels with transfusion. Hemoglobin levels below 95 can place great stress on the bones, spleen and aother organs. You may begin to notice skeletal weakness and facial changes.
Sending my best to your family,
Sharmin