Dogs are pack animals by nature so it sometimes takes a LOT of training to get them used to being alone.

And yes, I agree with those who say to leave the leash on in the house. Also, hopefully you are using a harness and not a neck collar. They're bad for puppies and can harm their trachea if she pulls and struggles on the leash a lot.

I definitely recommend puppy training classes. It helps a lot to understand why dogs do what they do and how to break habits you don't like. I'm a dog trainer and I think it's VERY important to at least attend training classes once in your life to understand the why's behind a dogs behavior. And I'm not talking PetSmart or Petco...I mean from a legitimate licensed trainer

Good luck!