A 7–year–old child presents to the paediatric clinic with ambiguous genitalia increasing with age. On examination, her height, weight and blood pressure were recorded within normal limits. Labia appeared bifid with 2 separate perineal openings, phallic length was 2.5 cm and no palpable gonads were noted in the inguinal region. USG shows the presence of Mullerian structures. The most probable diagnosis is –