Agree with pretty much everything posted above.
Definitely don't worry. You won't know until you try it and ship size is a personal preference thing.
If you do feel overwhelmed, just take a step back, don't try to go everywhere and do everything, stick to a handful of locations that suit you and branch out when you feel like it.
We loved this class when it was new. After several Oaisis class sailings, it actually felt a bit small to us when we did Independence last July and October but we still had a great time and it was a nice change of pace.