Should I get the 14 or the 21 day pass?

Hello everyone!
I am travelling to Japan from the 23rd April until the 10th May.
23rd arrival at Narita - transfer to Kyoto
Kyoto for 5 nights
Hiroshima/miyajima 1
Kanazawa 2
Takayama 2
Tokio 7 (it should be noted that the last 3 days I will be attending a seminar and therefore not touring at all)
I will have a total of 15 days for tourism and the last day I have to return from Chiba to Narita. So, should I get the 14 day pass and add any day pass for those 2 extra days or is it more convenient just to purchase the 21 day pass?
Thanks in advance!
Eugenia Bava