Have you taken her to a vet? You should check to see if she has a microchip. She might belong to someone. Have you looked online, called the local shelter, etc. to see if anyone has reported a missing dog? Also, a health check and a plan for vaccinations should be discussed with the vet. The vet might be able to locate a scar (or not) to determine if she has been spayed.
The chewing is normal. Labs and Weims are both high energy, smart, busy puppies, and both can be rather destructive when left to their own devices, when bored, under stimulated or under exercised. Weims typically require more exercise than Labs (there are exceptions to the rule) and need to run. This puppy will need daily exercise, potentially multiple times per day. Daily training, five minutes 3 - 5 times per day should be good. Training will help with mental stimulation, but an interactive food toy might help - stuffed Kong, snuffle mat, something like that. Don't forget socialization - look at a puppy obedience class locally to help. Finally, when you cannot watch the puppy, she needs to be crated so that she is not destroying your stuff and can't injure herself by chewing and/or swallowing something she shouldn't be.
I like these two free e-books for puppies:
Before You Get Your Puppy and After You Get Your Puppy
There are several more books to help (check out Puppies for Dummies) and obedience class will help also.
Good luck!