My 9 month old cries violently when I say "No!" in a louder-than-usual and stern voice. This happens when she bites me while nursing. Is it too early to discipline her?

If baby bites, it will be better to calmly unlatch baby and say nothing and end the nursing session. It is the most effective way to teach baby that nursing and biting do not go together. It is not a good idea to scream or yell on purpose as a method to stop biting. Some babies find it funny that they continue to bite for the reaction and some are so scared that they go on a nursing strike. My baby bites me when he is teething and I unlatch him and tell him, "you don't want to nurse anymore? Let's play some toys" and stop the nursing. If he is not full yet he will want to nurse again but this time round, he doesn't bite but if he does at times, I will repeat the procedure again.