Welcome to DT, your girl is a cutie!
I agree that she just sounds low key. My boy wasn't terribly interested in toys until he was about 6 months old. He plays with them now but not like the more energetic puppies. I have to ask, do you know much about dobermans? They are considered a very "velcro" breed that always wants to be with you. Your girl wanting to be by you always is NORMAL for the breed. Heck, most of us here can't go to the bathroom alone because our dogs want to be with us always.
Now, I know that you said that the "chin strap" was loose but it looks tight in every picture. I've honestly NEVER seen a posting job like that with so much tape. Just like Adara said, please make sure the ears have a chance to breath and also be sure that the tape isnt so tight that it's cutting off circulation in her ears.
Edit: Here is a typical picture of my pup at 14 weeks. Most of his pictures showed him with this expression and, as I said, he was never big on toys but just liked to follow his person around. He's more playful now that he's older but more-so with other dogs than with toys.