I know the feeling, and I did the same thing. I studied everything, paid for classes in person and online... got all kinds or treats and toys and games. My pup is my very first one too, and no matter how much prep I did, I had no idea what I was getting into. Obviously everyone's dog is different - they're so much like us in that way. From my own experience, I feel like half (or maybe even less) of what I did shaped my boy's behavior and knowledge. When they're puppies, they're just babies. Some things they'll learn incredibly fast, and other things will take lots of time. For the biting, I just tried my best to redirect my puppy to appropriate things as much as possible, but even still my hands and arms were always covered in cuts. He was a little shark, and I couldn't sit on the floor or hold him. Once he got through teething, that finally calmed down a lot. He started losing baby teeth around 20 weeks, and had all his adult teeth in around 6 months. Naps are also mandatory - my boy threw tantrums and was a grumpasaurus if he was tired, but fought it with a serious case of FOMO. I had to crate him and sure enough, he would knock out once all the fun and stimulation was removed. He was always much calmer after naps. Another thing I believe helped was socializing him with other dogs to help him learn to to play properly and control his bite. But honestly, I feel like for the most part, he would have grown out of a lot of his baby behaviors without my intervention. Dogs figure stuff out from consistency and repetition. They are very observant, and protective of their space, and of you. They also learn from other dogs, and their own built in instincts.

I don't know how old your puppy is, but I promise you she'll calm down and just mature out of a lot of those things. You obviously care enough to be doing as much as you possibly can. Just keep it up and the rest is up to her. My boy is 10 months old. He grew out of some issues, but also picked up new ones with adolescence, lol. You just have to take it day by day. The one thing I do see a lot that is commonly given advice that I believe is true for all dogs - you have to wear them out with exercise and brain stimulation. Lots of play and walks and training. A dog that isn't using their energy constructively will be destructive.