15 days in Japan

Hello!
We are travelling to Japan in April and May (Golden week). I've been reading about the transport but I got confused due to many available options. Also we'll be staying for 15 days.
I'm wondering if you could help advise with the below itinerary. Should we take a 7 or 14 days JRPass or no pass at all? And do you think it's better if we take the green pass as it is the Golden Week? Maybe we should get just the JR West tickets for Kyoto-Osaka-Tokyo? Too much questions? :) I'm panicking we won't get seats as we are arriving late to the airport and going directly to Kyoto. :)

1. Apr. Haneda - Kyoto
2. Apr. Kyoto
3. Apr. Kyoto
4. Apr. Kyoto
5. Apr. Kyoto
6. Apr. Kyoto - Osaka
7. Apr. Osaka
8. Apr. Osaka
9. May Osaka (Nara)
10. May Osaka - Tokyo
11. May Tokyo
12. May Tokyo
13. May Tokyo
14. May Tokyo
15. May Tokyo - Haneda

Thank you so much for your kind advice.