should i or should i not get the JR Pass?

Hi! My boyfriend and I are starting to plan our summer holiday trip. and I was wondering with all the trains I see in the itinerary if it would be a good idea to purchase the pass. We will start in Tokyo, then travel to Kyoto and Osaka and maybe do a quick escape to Nara; then we will travel to Okayama and visit the two islands Naoshima and Teshima. After that my idea was to visit Nagasaki and maybe squeeze in Kumamoto (I love Kumamon...).

Tokyo to Kyoto
Kyoto to Osaka
(Osaka to Nara Nara to Osaka)
Osaka to Okayama
Okayama to Nagasaki?
Okayama to Kumamoto?

When we get to either Kumamoto or Nagasaki the idea is to finish of the trip with a flight to Okinawa and then a flight back to Tokyo for some last shopping, as we will be returning home from Tokyo aswell. What do you guys think? Is it a crazy plan? Does it make sense? And should we get the passes or just buy the regular tickets for each trip?
Thank you for the kind help in advance!!!