No apologies necessary.
I'm no expert on this subject, so you need to confirm what I'm saying here (call NCL to clarify your options).
I believe that your FCC is now a cash reserve in your NCL account, to be used per regulations.
It should have no impact on what happens with this new cruise and getting a fresh FCC for this 2024 cruise to be used on that #3 if the price drops closer to your sailing date..
Again, remember that as you are more than 120 days out, you may cancel your 2024 cruise and rebook at the current rate. There is no limit on how many times you can do this before final payment.
Just two caveats: any special promotions you received (such as OBC) will be cancelled - you will receive any that are currently offered; also, I think there may be a complication if you took the BOGO air option.
Good luck.