Need to change plans, not sure what’s the best way to proceed.

Hello, I need some help, I have bought tickets for 3 weeks (April 7th – 29th), I would land in KIX on the 8th of April. I have gone through several iterations of my itinerary, but the plan that I settled for is this:

April 8: Arrive in KIX, fly to Yakushima

April 9-12: Yakushima

April 13: Ferry to Kagoshima

April 14-15: Kagoshima, and cycling around Sakurajima if the volcano is being nice.

April 16: Take the bullet train to Kumamoto, rent a car there and drive to Takachiho gorge and the Amanoiwato Shrine

April 17: Drive to Kurokawa Onsen, on the way there stop at Kamishikimi Kumanoimasu Shrine AND Daikanbo lookout, finally arrive there and spend the night

April 18: Onsen hopping in Kurokawa

April 19: Drive to the Kokonoe Yume suspension bridge, and spend the night in Yufuin

April 20-21: Beppu and Oita

April 22-24: Go from Oita to Fukuoka by train.

April 25: Yutoku Inari shrine on the way to Nagasaki

April 26-27: Nagasaki

April 28: I had saved one day as extra to allocate where I felt It could be used the most

April 29: Fly from Nagasaki to Osaka, my flight from KIX is around 10:30pm so there's time.

Now for the problem, so I didn't quite realize that it appears there's only 1 flight per day that goes from Osaka Atami airport to Yakushima, and I can't make that flight.

So my question is… What is the best way to pivot this? I thought about Starting in Fukuoka or Kagoshima, but these locations would be messier than I would like routing wise. Another option would be to just spend the night in Osaka and take the flight the next day, but this feels kinda bad, as it feels like I am starting my trip behind already. Finally, the last thing I considered is reintroducing Hiroshima and Miyajima into the trip, I initially had these places in my itinerary, but I removed them because I thought I want to focus more on Kyushu and go at a bit of a slower pace, but maybe now that becomes viable again, I could remove some lower priority/interest targets such as Yufuin, Beppu and Oita to add 2 full days in Hiroshima not counting the arrival day into Hiroshima itself, plus spending a night in Miyajima.

by WhyAmIhere77