Hurricane season is June 1-November 30, so any summer sailing is potentially at risk. We just sailed Aug 22-26 and had beautiful weather. Previously sailed September 15-17 in 2017 and were in between two hurricanes - Irma and I think Maria - and at least the cruise before ours was canceled. Other than really cloudy water at Castaway Cay, our cruise was wonderful and you really wouldn't have known. (Our week after in WDW however was actually more affected by Irma with some of the behind the scenes stuff we had booked canceled, trees down everywhere, etc.)
Disney does a really great job of watching the storms so that you don't have to. If they cancel, they will give you as much notice as they can and typically offer a discount on a different sailing.
I say stick with your booking - add
travel insurance, which you really should do for a cruise anyway, and don't sweat it.