That's not exactly abnormal for a dog, particularly a puppy.She is the sweetest girl in the world .. but you talk to her sometimes and its like she is looking right through you!
I would have her fully checked out by a vet. Make sure she doesn't have a UTI or parasites or any problem that could be causing her pain or discomfort. It's awfully hard to learn if you are in pain or just feel sick.
Then I would get a positive trainer in to help you. It's possible that you just aren't training correctly and a trainer could help you with that. Maybe she is stupid or brain damaged, and if you add that to poor training, you can't expect much.
My dog, Kabota, seemed really stupid for about 3 months after I got him. He was just very stressed out from all the changes in his life and once he calmed down and settled in, he started doing much better with training. So hang in there, get some professional help and have patience.