I remember posting this exact same question here about a year and a half ago! So I feel for you. Daisy was an absolute terror when she was a puppy. She would literally run across the room when my kids were sitting on the floor and jump up in their faces and bite them! I posted here for advice, I spoke to a trainer, I spoke to the breeder, etc. I actually considered returning her to the breeder, it was so bad. And given that I waited 15 years to get her and researched the breed for about 2 years before getting her, that tells you how upset and concerned I was!
I'm not sure what finally worked with her. It was a combination of things, but one thing I definitely think helped was showing dominance over her when she got aggressive with the kids. I would step between them and her and move forward toward Daisy pointing at her and saying "no" sternly when she was being too rough. That let her know that I was disagreeing with her behavior. We also did puppy kindergarten and Obedience I. So she got used to watching me for cues as to what was expected of her. Yelping when she bit us wasn't working too well with her, but I certainly believe it works for some dogs. But as Karlin said, maybe I just wasn't very good at it!
I never was much of an actress.
She is the best dog in the world now (an unbiased opinion, I'm sure
). I am so glad we made it through that period. It truly is a puppy thing and it will get better, so take comfort in that. Daisy is gentle and sweet with everyone now, even young kids. Thank God we stuck it out through those days of stress and frustration. Next time I get a puppy, I will be more prepared for all of that, but it definitely came as a shock with Daisy. She was a very bossy assertive little thing. We had toy poodles growing up, so I had experience with 4 poodle puppies over the years. They nipped, pulled at pants legs, etc. like all puppies, but NOTHING like we went through with Daisy.
So stick with her and try to be consistent with showing her you don't like that biting behavior in whatever way you think works best for her, and it WILL get better!