Hi: wow...your first is on Carnival and now you are going on Princess. You will be amamzed. We did it in the opposite way. Princess then Carnival. Two different styled cruise line I think.
About comparing prices paid. I agree with all the above folks. It's like playing a slot machine and you are having no luck. When you get up to leave it, run. do not walk away. Do not look back else someone sits down and you see the first quater pay off big. Best not to think about it.
Have a great cruise. I love Princess.