Maximise JR Pass

Hi,
Me and my boys (13 and 9) will be going to Japan next year and traveling to 7 cities for a total of 18 days. But I am not sure if the 14-day pass is enough for us.

Our Itineraries are:
Tokyo = 2 nights
Hakone = 1 nights
Kyoto = 3 nights
Osaka = 5 nights
Day trip to Nara, Kobe, and Hiroshima Tokyo = 5 nights
Day trip to Fuji-Q highland, Disneyland, Disneysea, and a few places in Tokyo.

And also I am confused about what train tickets to get to go to Fuji-Q highland. I was thinking to buy the Hakone pass to go to Hakone and use/activate the JR pass from Hakone to Osaka??

Will appreciate your help, we are all excited to go to Japan next year. The accommodations are all booked!!