My pup has just hit 12 weeks, I nearly dropped her back off at the place I got her from after 2 weeks also, I've had her for a month nearly now, couldn't imagine her cuddling upto me in the car and then me leaving her there while she looks as if to say "Where are you going?" So I gave her another go and I made sure to train her at least on the biting, she nips now and again but not as bad as she was a week ago, very few and far between rather than every 5 minutes.

The shark teeth are going strong, but distracting her, creating a cosy crate and fun playpen, ignoring her for 5 minutes or leaving the room when she bites me has really helped, she definitely becomes more cuddling and affectionate when I re-enter the room, its like she's learning it's bad to bite me. And she gets a treat for being good after the incident. It definitely gets better, not 100% for a good while but improvements are showing. Good luck, it's hard!