Are you sure there's been no progress? Are you keeping measurements or taking pictures?
How much pressure are you using? Maybe it's not enough. Do you get any swelling at all after pumping?
What are your starting stats? If you're starting with very little breast tissue (AA or less) then it'll take a lot longer to see any results. It takes some people half a year or more to see changes, so don't give up!
What have you tried so far? Maybe switching it up would help you, trying different methods like hydronoogling, the 7:2 method, doing shorter sessions twice a day, massaging etc.