High reps made my legs grow fast. I wasted money on some good pants back in the day because I couldnt even wear them again. Low reps gives me better strength gains but almost no size gains. The only advice I can come up with is heavy low rep squats. They work the glutes and thighs and you will have the benefit of looking like you work out but will not add mass so quickly, so the rest of your body will grow at a faster pace to catch up