theres a girl on youtube who has a few flexing vids... average sized girl, 14-15yo, 5'4/114lbs... hers go from 10.25" to 11.75"... thats huge, 1.5" growth... they just pop when she flexes... bigger than mine, and i'm an adult... by the way, whats ur height, weight, u sound pretty skinny, altho i bet thats about the size i was at ur age...