My hook an loop diapers (bum genius, thirsties covers) aren't holding up as well as I had hoped. Am I doing something wrong??? I wash them all together --prewash in cold water and then wash with detergent in hot. I line dry them and then I will sometimes put them in the dryer. I've noticed that the strip that the velcro tabs attach to is pilling and pulling away from the diaper. Ideas? How can I prevent this from happening?