You certainly don't have a card for each scene in the novel, but you have the scenes that your subconscious seems to want to deal with. You also have numerous gaps. Now you turn your thoughts to just those gaps, and new ideas occur to you. That means more cards. Maybe some of the new ideas are better than the original ones, so some of the old cards go in the trash.
New characters emerge to fulfill functions in the story.
The story may eventually end up as a series of flashbacks, but for now stick to straight chronological order. Keep asking yourself why . Don't keep a scene in your storyboard unless you can justify it as a way to dramatize a character's personality, to move the story ahead, to lend verisimilitude. Once you have at least the main sequence of events clearly mapped out on your cards, you can begin to transfer them to a more manageable synopsis or outline.