Hi there!
To understand if a 7 day (¥28,300) or 14 day (¥45,100) rail pass makes sense for you lets first take a look at your projected ticket costs (including your 'maybe' destinations):
- Narita airport terminal 1 > Tokyo: ¥2940, (62mins, 79km)
- Tokyo > Kyoto: ¥13220, (164mins, 513km)
- Kyoto > Nara: ¥690, (45mins, 41km)
- Nara > Kyoto: ¥690, (44mins, 41km)
- Kyoto > Nagoya: ¥5440, (49mins, 147km)
- Nagoya > Tokyo: ¥10580, (106mins, 366km)
- Tokyo > Nagoya: ¥10580, (126mins, 366km)
- Nagoya > Tokyo: ¥10580, (106mins, 366km)
- Tokyo > Yokohama: ¥1460, (23mins, 28km)
- Yokohama > Tokyo: ¥450, (27mins, 28km)
- Tokyo > Narita airport terminal 1: ¥2940, (58mins, 79km)
TOTAL: ¥59570 for 11 legs
As you can see, based on these costs, you will make large savings using either the 7 or 14 day pass. I think the deciding factor about which pass you decide to get will depend on when you do your final Nagoya > Tokyo trip. As you can see these are expensive trips, and if they are after day 7 while you are in Japan will mean you should go for the 14 day pass. If your last Nagoya trips are done within the first 7 day period, then I recommend you purchase a 7 day pass for maximum savings.
Hope this helps!