Hi, Loveable, and welcome to cruise-chat.
Unfortunately, the weeks you mentioned are well in demand as both are school vacation weeks in the NYC area. My niece tried to book a cruise out of NYC the week of April 1st and could find nothing. She ended up finding a cruise out of Houston (Norwegian Dream) and the airfare was lower than she had expected. She said it would have cost a great deal more to fly to Florida (along with many other NY'ers).
Best of luck with your search.