Puppy Biting help! How much is normal?

My 16 week goldendoddle has been chewing alot however she keeps on nipping/biting people Ive tried the yelping method, the stern no, and then proper toy. However I am just worried because i don't know if this is normal? I looked up signs of puppy aggression and she doesn't really have any of those signs. Also there are two older dogs in the house and she roughhouses to the extreme with them. They do not show any signs of aggression when playing. ie tail, arched back, ect. Should I intervene I don't want her to think she can pounce on any dog. She will be starting puppy obedience classes in two weeks.