I wouldn't agree that she's getting agressive-more likely she's getting stronger and more energetic as she grows up.
He's one, and she's under age-I just simply would not allow the pup around the baby until the pup is older and through the puppy stage.
The baby very well could whimper and she might get MORE excited (prey drive right? If they catch an animal it cries too and this excites them-as well toys squeak right? There is a reason for it
) and it could easily turn into a game. She's just too young to expect her to know to leave the baby alone.
I wouldn't allow her around the baby unsupervised, and if she is chewing on him-put him in playpen or another room or up high etc.
For teething-a great thing we've always done (She is likely teething now or very soon) is wet a towel, tie it in a knot and freeze it. It's hard and crunchy and cool to chew on-feels very good for them
Puppies do mouth and chew, it's normal I wouldn't be overly concerned at this point-just prevent her from chewing on the baby.