When you're stuck try using an aerial  keyblade or strength  type to get those hidden treasure chests. By getting everything and beating all of the callenges, you should unlock the soul of sora item in the shop and it costs a lot of points just to get. if you do'nt have him now  chek again because by now you should have beaten the game already.

Hint to skip to event days you may be able to touch the advance button at the top left of the bottom screen