creatine does cause fluid retention..but, even if you take more and more, you won't continue to gain more and more water weight..you will retain the fluid with the supplementation, but only up to a given point..if you are stuck at a weight, it is most likely because of your diet
carbs also cause water retention...for every gram of stored glycogen, your body retains ~3g of water that you ingest (maybe a little less) to balance a sodium response to the carbs
so you could be holding fluid for multiple reasons
also, this is a decent study looking at creatine and water retention if you care enough to read it:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC155510/