Papa55- I'm in Portsmouth, NH and we typically find affordable airfare out of Boston to Fort Lauderdale on Jet Blue- direct flight. Not sure what you paid for airfare through Carnival but we got flights for $379 per person, round trip in March which is over spring break. Not a bad price considering it a busy travel week and we booked the flights a month ago. You could also consider flying Jet Blue out of Portland but you would have to grab a connecting flight in NY.
Of course, I'm taking on some risk by booking air on my own but it's worth it if you plan accordingly. We are flying in a day early just in case it snows...with my luck, it will
Have a great cruise!