Enjoy your trip. You will have a great time.

We have always travelled to Greece in May and I am sure that on all 6 visits there was a threatened Ferry strike in May. Tourism is far too important to the Greek economy and somehow they all got settled at the last minute.
I'd suggest you simply remain flexable and go where the spirit moves you. There are many stories of travellers who landed on an Island, fell in love with the island and spent their whole vacation there.