What Breed Is My Dog?

I adopted Pepper from the shelter about a month ago, rescued her from the euth list. She was 24 lbs when I got her. Pepper has already been examined by the vet, spayed and vaccinated. Pepper is estimated to be between 7 and 12 months old. She weighs 29 lbs now. The vet says she is a mix between a Lab and a Pit, with a partial purple tongue and a tail curling over her back, and she has webbed feet.

I have no experience with pits, but I am a dog owner of one grown Black Lab, one Lab/Chow mix currently, and a Rotti previously. I just wonder about her temperament. She is out of control in her jumping, barking, licking, playfully biting and running, and destroying things. She loves to play fetch, and seems really smart, but
stubborn. I know some of these behaviors are puppy traits. Though she does not behave like a Lab at all. If she is part Pit, what do I need to pay attention to? And how much bigger do you think she is going to get? Thanks!