Welcome - but be careful, because this site is addictive! It sounds as if you have a cardboard box junkie - a quite common affliction. Our cat doesn't chew the boxes, but he sleeps and plays in them, and rubs himself against them all the time. At first I was afraid that he was "sniffing glue", but then found that he reacted the same way to boxes that were taped, stapled or unsealed, so it must be the cardboard. He gets all excited when he sees the UPS or P.O. delivery truck, since that usually means a new cardboard box! For the past five years, almost, a cardboard box has been a living room fixture. As long as your cat isn't actually eating the cardboard, I wouldn't worry about it. Let her have her fun.