I would contact port auth. Parking not under carnival's control, its part of the port auth. If you log onto mobile al. web there is a link with information with phone numbers you could call them.
mzladyjava:from the parking lot to check in point?
This is pretty much one in the same, elevator or stairs from them level you are parked to main terminal level.
I didn't think it was a far walk, we happened to park about 50 yards from the elevator. When you pull into parking area there will be all kinks of people to help you, they will take your bags for you, they even asked me if I wanted to stay in our vehicle. So I think you will be fine.
As far as traveling alone, sounds like you need someone to go along to help out (hint hint). Just looking for an excuse to go on another cruise...LOL!
I don't think you will have any problems. Someone is always there to assist you form what I saw. Have fun and have a great cruise.