Keep in mind that she came from a Pet Store, meaning Puppymill Puppy…. she was taken way to early from both her Mom and her littermates before she had time to learn many things from them... number one being bite inhibition, critical early development from adults and littermates, mouthing is normal learning for puppies... and if they miss that early socialization it makes it twice as difficult when they are older.... I agree with agilebasenji about finding a trainer ... but also try working her mind.... with sits, downs, stay, hide and seek, all kinds of things that you can do. When she becomes over excited, revert to working her mind. She doesn't have to do them perfect... but make her mind work for treats/pets.
Old school was the "power play"... over used and not really effective... as if there is a real struggle, for sure you will lose.... being Alpha is not based on who is stronger, because the dog will always win, if they want.
ps... welcome to the forum... while I live in California now, I was born and raised in Bucks County!