Timeouts not working, and a defiant pup

So my dog has been having a lot of behavioral issues since I got her, the most recent being tearing at the carpet. (At this point my poet deposit wont even cover it she's cost me a fortune already)/ Despite getting plenty of exercise, having dozens of fun toys, she still digs at and tears up the carpet. Other issues like digging at my bed sheets, or barking have been a problem as well. And I always put her on timeout when I catch her doing anything wrong. It's an empty room for her to be alone for a minute or two before coming back. At first, timeouts were becoming very effective at stopping behaviors such as unwanted barking late at night, or chewing up things she wasnt supposed to. And now all of a sudden they have completely stopped working. Is there any other training strategy that i can use to show her what works and what doesnt? After 2 months of having her it has proven rather difficult to find out the best training tactics for her. Despite all the methods I have tried and all the work I've put into correcting her previous owners shortcomings. She's a smart dog, she's just obnoxiously defiant and it's almost like she gets a kick out of intentionally ignoring redirection and correction of her behaviors. I have switched training treats several times to get her motivation for training up, and to give her a better reason to do what I want but it still doesnt work. I have tried getting anti chew sprays for my carpet, they dont work. I have tried getting her more toys, I have tried wearing her out more. And I just resorted to blocking off the spots she chews and digs at, but that is a temporary solution. What are some other effective ways to show my dog what works and what doesnt, since timeouts are proving so ineffective. I should add that she is about 7 months old give or take a few weeks, could all this defiance be just a thing relative to her age and her "teenage phase" and is it something that will go away, or is it something about her individually?