I have a 3mo old GSD - a few questions, BYB's, etc?

The dog is 6 weeks old so: It's definitely from a BYB breeder. No taking a pup away from it's mother at 6 weeks as opposed to 8 weeks doesn't make it aggressive. That's hogwash. There's a lot of crap being said about that little 2 week difference. Honestly I prefer the pups stay with their mom and littermates until 8 weeks for health and socialization (not so much for socializing but more so for FUN, yeah pups like to have fun too!). Health wise, some 6 week old pups dehydrate easily and it's just safer to keep them with mom. As far as "bite inhibition" which also, is hogwash, keeping a pup another 2 weeks does nothing. Bite Inhibition exists but the petsmart yuppy crowd took it in the most stupid way by yelping and telling other impressionable people to "yelp" like a littermate of the pup and then to ignore it. this is what a WEAK puppy does when it's hurt, you're not trying to play the role of weaker sibling, you're trying to play the role of stronger pack leader! Pack leaders don't yelp, they give corrections! So when she bites on you, grab her little collar and give it a sharp tug and a no. Be very forward with her, square and forward while saying "No", body language is key here. As far as the Peanut situation goes, correct the pup for pestering Peanut, it's cute now, it won't be cute when she's 10 times Peanut's size. Peanut's doing the right thing, she is trying to correct the bad mannered pup, now THAT'S bite inhibition, not that crying yelping crap...take notes from nature and not idiots at petsmart, lol. Also (nearly forgot) you talked about her hopefully being stable. Was she frightened of you? She seems to be a pretty confident and outgoing pup, if that's the case hopefully you won't have any problems. just keep in mind she's not a 5 pound chihuahua and needs discipline and training. I hope I helped and good luck!