Puppy will not stop biting me

So my friends found a little puppy dumped in a park a week ago. It was 6 PM, she was on hole 10 of a disc golf course deep in the woods nobody was around. She’s only 12 weeks old and temperatures dropped to 32° that night so she probably wouldn’t have survived. Not an important detail, but it still hurts my heart to think of what would’ve happened had they not found her. She was stained with her urine and feces and starving so she was obviously dumped. They couldn’t take her so they asked if we could and since we foster dogs, we took her in. Contacted animal care & control, all that, nobody claimed her in the week she’s had her. We took her to the vet, found out she was parvo positive so she’s been quarantined from our other dogs (we had her quarantined anyway as that’s what we do for 3 days with fosters and since she had never been to the vet, we knew there was a risk so I’m glad we were safe).

Now, we are not sure if we’re keeping her. The shelter said after 30 days she’s ours or we can contact a rescue and put her up for adoption. There’s lots of reasons we will or won’t keep her, we’re weighing it all right now but that’s neither here nor there because we are struggling while we do have her. (We will not take her to a shelter, we foster so this isn’t new to us but a puppy is).

She will NOT stop biting us. We visit her every 2-3 hours for at least 30 minutes as she’s in our foster room in our basement at the moment and cannot be with our dogs for another 3 days. We know she’s teething, we know this is normal but no matter what we do she is not deterred. When she starts biting, we stand up and walk away. She just follows us and sits in front of us. Then we sit down with her and does it all over again. This goes on for 10-15 minutes but it never stops. We try to give her a toy but she just immediately goes for our hands. My hands are COVERED in bites and scratches.

She has a whole bin of toys down there, all scattered around her room. I have a 1 year old dog who I have all her puppy and stimulation toys from training her. She gets a frozen kong twice a day, she has teething toys and I know she’s uses them because she has them in her bed in her kennel. (She has a whole room to herself equipped with a covered kennel but the door is left open, a large bed with blankets on it, she has a fluffy bed in the kennel and the kennel is filled with blankets and then toys everywhere.)

Is she bored? I feel terrible that she can’t be with us upstairs but the vet said to keep her quarantined for a week even though she’s not showing signs of parvo, it was a faint positive and she could be fine but it was better to be safe than sorry. Our girls are vaccinated but the vet said it’s not worth the risk and we’re heeding that advice.

I’m doing my best with visiting her, giving her all the toys she can ask for, frozen treats, stimulation and playtime when I’m with her but I cannot handle this biting anymore when no matter what I do it doesn’t seem to make a difference.

If it helps to know her breed we believe she’s a pitty.

Shes perfect otherwise. Has 1 accident on a towel in the 8 hour nighttime, goes straight to pee and poop when we take her outside, knows sit and come, and all that but this biting is just not giving up. If we take our hand away sometimes she starts growling and showing her teeth, is that common or something bigger?

We introduce her to our dogs on Tuesday, and I’m worried about her biting them. They’ll be supervised at all times but we’ve been working on this biting for a week with no progress.

Any tips appreciated! Also, if you have any toys or homemade items that helped with your puppy teething that’d be amazing!