Circe is a beautiful name. I'll add my vote to the "give her time" column. Some other random comments:
1) Since she enjoys running in your BF's mother's yard, try engaging her there. Act silly and pretend to chase or run from her. Do the human version of a playbow. Try tossing an animal-looking stuffy in front of her as she's zooming around and see if she goes for it. If nothing else, practice the "come" command with lots of praise and rewards once she's gotten her ya-ya's out.
2) Large amounts of poop and farts -- this can be a grey's reaction to the stress of adjustment, or it could mean she would digest another food better. Or both. You might want to think about cautiously transitioning her to another food.
3) Growling over a threatened pig's ear -- There are different philosophies of dealing with growling at a human, but I belong to the Zero Tolerance school. I use the Voice of God and body language to demand the dog back off the treat, fast. Then I praise. Other, smarter people start training by letting the dog trade up to an even yummier treat as a reward for "drop it" or "leave it." Also, the pig ear might be contributing to the problem above.
4) As suggested before, can you meet up with other dogs/humans for a fun playdate? Another grey might be best for relaxation for her and talking with other grey folks for you.
Best wishes for you and your pup!