No change to lips after filler, how much does one need to notice a difference? (photos)

I find that 1cc is often enough to give a nice natural plumping to lips and restore some natural volume loss. @cc would really enlarge the lips. It is possible the injector is injecting to posterior ( deeper inside ) ad deep into the lip which will make the outcome less obvious. I would recommend injection along the dry outer part of the pink lip. 

Hello and thanks for the question,
I am quite surpised that you have found no difference as 1ml of filler usually makes a very significant change. Although practitioners do vary, I have never used more than 1ml at a time and have not yet found a patient who hasn't had a very noticeble difference from this sort of volume. 
The only reason that I can think of, is your perception of your lips being back to their normal volume after the swelling has settled. Do you have photos of your lips before and after from the treatments (from the same angle with a normal resting expression)?
If you are disappointed I would certainly suggest going back your practitioner and discussing this further.
Good luck!
Dr Chris Macdonald