I feel for you I really do.
When we got Willow she was like a whirlwind. I never estimated just how much hard work she would be. Its mine and my OH's first dog together and boy was it a learning curve.
Willows puppy biting, I felt was out of control and one day she dived at my OH's face and he came running into the bathroom face in hand telling me he was going to have to go to A and E. Of course he didnt and we can laugh about it now but a the time its emotionally draining. I cried most days and one day when my OH came home from work I questioned him as to whether we had done the right thing in having her.
We used a house line as mentioned above and it was great, every time she got out of control we led her out into the hall way and left her there for a few minutes, only allowing her back in when she was quiet. Initially we would lead her out and when we let her back in she seemed to do it again so back out we would go,often up to about 8 times, but they are smart dogs and a few days in she got it. Willow seemed more nippy when she was tired/over tired. When I realised this, when she had calmed a little I would pop her in her crate to sleep and recharge her batteries.
When they do get bitey its always good to have something they can chew on to distract them with.
As mentioned above clicker training is fab, Willow is a working strain dog and I found that tiring her out mentally was far batter than tiring her out physically. I would do it at a guess 6 to 8 times a day but only for a few minutes at a time
On the whole when reading above it seems like she is doing so well in other areas so far. Well done. Keep up the good work. In a few months you will look back and this will all be a distance memory, honest