I am no doctor, but I was told that if you dont see any results after 6 months it is highly unlikely that you see any results.
Having said that there is a big difference on how the different PPI's work on us, so be sure to try different types.
I am not sure about the us names, but you should at least try:
Lansoprazole works on me, but not 100%. Nexium has no effect. Actually I experienced that some brands of Lansoprazole doesn't work either.