From what I can see you are so focused on correction and teaching your dog what NOT to do that I don't believe you have offered instruction in what you want the dog TO do.
This is so true - it pretty well sums up any training I've ever done with my dogs. I'm not going to be able to help you with keeping Bubbles from biting you, since I encourage this behavior. But keep in mind that she's not 'biting' you: what she's doing is 'mouthing' and she's like every other GSD puppy out there - they call them "landsharks" for a reason, lol. She wants to play with you and this is how they initiate it.
Human babies put everything in their mouths too, to explore. It's so normal and to be expected from puppies as well. It's too bad that their teeth are so sharp, but it's also a good thing, because when they bite too hard with each other they learn not to use so much pressure because whichever one gets the bite will yelp, or even stop playing. They learn not to bite so hard this way, because they want to play all day - until they're too tired to keep it up anymore.
When I teach my puppy not to bite hard, I stop playing just before it hurts too much. The worst thing, IMO, is when you grab their muzzles when they bite, because this is just too rough. It'll escalate the intensity, which is the exact opposite of what I'm trying to teach. I don't want the game to get rougher, I want it to get gentler. So this is probably why Bubbles is getting you so frustrated since she's probably getting way too rough and you think she's being aggressive, but she's just playing the game you taught her by mistake.
What toys are you using to redirect her mouthing? This is the only thing that worked for DH, because he doesn't agree with me and wouldn't let my puppy mouth him. He tried holding his muzzle, because that worked for him with different breeds (lol) but he found out the hard way that my puppy liked that even more, and came back at him twice as hard. I told him not to do that, to shove toys in his mouth, but not let go of the toy - keep him engaged in a chewy fun game. It's not like putting a pacifier in a baby's mouth because a puppy won't be satisfied with just a plug, they want games. Lots of playing, lots of games, lots of chewing.
When my puppy wasn't playing chewing games with us, he chewed on bones. When he wasn't chewing, he was sleeping. LOL, but I'm not kidding.
Does Bubbles have any bones that she can chew when she needs to? Part of the problem is that they're teething, so they want something to chew on, so you need to give them something: bones, kongs, rope toys, whatever she'll enjoy.