If she is pulling fur, shes bitting. Nipping is a quick little peck, so to speak
It seems to be a dominance thing. She wants to be the alpha, and she wants to be shown that she is the alpha. When he puts his head down in front of her, he is asking to be groomed, which is his way of claiming dominance over her (thankfully he doesnt care about mounting or anything worse). But, she doesnt like that. You can try to rub in a bit of apple juice onto the fur of her head, or mash in a bit of banana to the fer on her head. This should get your male to start grooming her, which will hopefully make her feel more secure in being the boss over him
The only other thing i can think of is that her hormones havent drained yet. Females can take up to six months for their hormones to fully drain from their body
Google says you can try distracting her. When she bites him and starts to pull his fur, move him away from her, pet them both for about a minute, them give them both different toys, preferably wood or cardboard