If she is eating, drinking, pooping normally, and is active I doubt there is any reason for concern.
When you hold her up near your ear, do you hear any "clicking" sounds when she breathes?
Budgies normally make many different types of sounds - "cooing, chirping, singing, scolding, etc."
Without us hearing what you are hearing it is difficult to give a valid assessment but it does not sound like something to worry about.
If you are particularly concerned, you can upload a video with audio to the forum in this thread so we can hear the sounds you are worried about.