A 28-year-old woman presents with progressive bilateral hearing loss over the past 2 years. She reports tinnitus and occasional vertigo. Her mother had similar hearing problems starting in her 20s. Otoscopic examination is normal. Audiometry shows bone conduction thresholds better than air conduction thresholds (air-bone gap of 30 dB). Weber test shows lateralization to the right ear. What is the most likely diagnosis?