A 34-year-old male presents with dizziness and fatigue for more than 2 years, worsened with jaundice for 1 month. Lab results: Hb 50g/L, WBC 3.0×10⁹/L, platelets 48×10⁹/L, reticulocyte count 0.20 (20%), bone marrow smear showing active proliferation (erythroid series 53%, predominantly intermediate and late normoblasts), urine bilirubin negative, urine urobilinogen 1:320 positive, urine hemosiderin positive, serum ferritin 12 μg/L. The most likely diagnosis is: