How do i show my puppy that i am the pack leader?

i have two puppies, both sisters and they are 8 weeks old. one of them, Jess, already considers me her pack leader as i found out today, she followed me as i got ready and lay in the doorway of the bathroom when i put my makeup on, but the other one, Milly, i think is the more dominant one between the two, because she is the one who always seems to be "on top" in play fights and Jess always rolls on her back, but that means that Milly thinks i am below her too, i tried things like putting my chin and neck over hers and she growled but Jess didn't. so how can i show her that i am pack-leader?