Devo,
I would soldier on with ignoring your puppy completely for doing the wrong thing. If you wish to say something try "oops" and then reward immediately the calm behaviour that you want. It is hard to scream "oops" at your puppy, but if you would like to give him some feedback that he has not suceeded in gaining a reward from you, this could be a word you use.
You don't want to be punishing a new puppy by screaming at it. and as you said, he just keeps on going with his biting. No punishment working there or the behaviour would have stopped.
Pups mouth really badly around 12-14 weeks old, owners must do their upmost to ignore, if it means removing the puppy from you if the puppy is really excited, than do so. Not as a punishment or a sinbin, but as time away from you where the puppy is not practising the behaviour. Yelling or saying no to a dog does nothing at all.
Good Luck