Hey Maya -
I hear you on how hard puppies are. Take a deep breath! I hope you have a good breeder you can lean on for some support?
I have a 3 month old pup, so I'm right there with you on being sleep deprived, and I'm in the midst of potty training and all of it. Since Leon is my fifth Doberman, I can tell you with confidence that it does get better, but raising a puppy - any puppy - is hard. If you want to do it, you can!
Right now, your crate, an x-pen, and good chews are your friend. I have two crates and an x-pen set up for Leon. We are doing our best to have a schedule for him so he gets used to things. I saw your other thread. Leon also came home on Inukshuk and I didn't change anything for a while. I added a bit of water and a probiotic to his food. I would be sure your pup's cone is off for meal times. It can help to feed in the crate, both for crate training and to minimize distraction.
Sometimes puppies need to go really often! Depending on how much water he might have had, or how active he's been...we might need to go out 15 or 20 minutes after we were just out. Leon doesn't really have any freedom right now. He's either in his x-pen, or gated in the room with my eyes on him constantly, or he's in a crate. If he's "out" in the room, he pretty much goes outside ever 20-30 minutes. I try hard not to give him a chance to make a potty training mistake. If he doesn't go, we go back out pretty soon after. If I really think he needs to pee, I'd probably stay out long enough that he does go. You might need to put him on a leash if he's distracted outside.
The biting...yep. You've gotten some advice already, but I've found the biting is the worst when Leon is overtired and needs a nap. Also, I offer him lots of chews. We do a lot of bully sticks, we do chews from Farm Hounds - the beef hide rolls, we do some beef cheeks... the more things he has that he likes to chew, the less likely he is to bite. It's worth the money! You can also buy some things like Toppls and stuff them. It's really a good idea to offer him something to chew in his crate when you leave him alone to go upstairs, even for a few minutes. That will help with the whining.
What else? Happy to brainstorm with you.