A 38-year-old woman from rural Maharashtra presents with progressive fatigue, dyspnea on exertion, and palpitations for 6 months. She reports heavy menstrual bleeding for the past 2 years. On examination, she is pale with a hemoglobin of 7.2 g/dL. Blood smear shows microcytic, hypochromic RBCs with anisocytosis. Serum ferritin is 12 ng/mL (normal 30–300), and serum iron is 35 μg/dL (normal 60–170). TIBC is 420 μg/dL (normal 250–425). What is the most likely diagnosis?