A 38-year-old woman from rural Maharashtra presents with a 3-month history of progressive fatigue, recurrent infections, and spontaneous bruising. On examination, she has pallor, hepatosplenomegaly, and petechiae. Complete blood count shows hemoglobin 7.2 g/dL, WBC 2800/μL, and platelets 45,000/μL. Peripheral blood smear reveals normocytic RBCs with no dysplastic features. Reticulocyte count is 0.8%. What is the most appropriate next step in management?