Most studies in the literature that try to correlate size of the syrinx with clinical symptoms do not use the absolute size of the syrinx alone. Rather, they take the syrinx size and compare it with the size of the spinal cord and come up with the ratio. 2mm is quite small and keep in mind that it's extremely difficult to make a clinical comment regarding an MRI I have never seen, but I would say that it's not impossible for it to be causing some of your symptoms. I would of course personally have to examine you and review your films and history to make a more accurate comment. If the symptoms worsen, consider getting a followup MRI for comparison. Good luck.
A related discussion, Syrinx question was started.