Travelling to Japan in Dec

Hello,

My family and I will be travelling to Japan (11 days, 10 nights), with plan as follow:
- arrive in Kansai Airport Osaka, spend 4 nights. - during our stay in Osaka, will travel to Kobe, Kyoto, Universal Studio and surrounding Osaka - then heading to Fujikawaguchiko for 2 nights: visiting Mount Fuji and Gotemba - then we will spend 4 nights at Tokyo - beside spending time in Tokyo (shibuya, shinjuku, DisneySea), we will visit Yokohama - finally we will depart from Haneda airport

We are considering to take the JR Pass, as we understand, beside the train between city, it can be used during our sightseeing in Tokyo (not sure in Osaka city). However we confuse between 7 or 14 days.
Which option you may advise a better one:
- purchase a 14 days JR Pass to cover all days of our travel - purchase a 7 days JR Pass, then to add it with Tokyo Metro Pass (to cover city sightseeing)

Thanks for your feedback. Warm regards