A 31-year-old woman presents complaining of fatigue, shortness of breath on exertion, and occasional palpitations for the past few months. A full blood count (FBC) reveals: Haemoglobin (Hb) 102 g/L (115-165), Mean Corpuscular Volume (MCV) 72 fL (80-100), Red Blood Cell Count (RCC) 3.8 x10^12/L (4.0-5.2), White Cell Count (WCC) 6.5 x10^9/L (4.0-11.0), Platelets 250 x10^9/L (150-400). Iron studies show: Serum Ferritin 6 ng/mL (15-300), Transferrin Saturation 8% (20-50%). What is the most likely diagnosis?