I am sorry that the route that you chose to take is limiting your ability to get a refund. As many are learning due to the pandemic, there is no benefit to cancelling sooner than needed (unless you were required to make an additional payment toward the cruise). If you had waited until the cruise line cancelled you would be in a much stronger position to receive a refund. Did your agent advise you of this? The fact that all travel industry companies are receiving very little business (equates to no cash) throughout this year, the chance of you receiving a refund are quite slim as those companies need to refund their customers who ARE due a refund. Unfortunately, you are not. While you and your husband may fall into the group that may be at higher risk of catching covid, most people who cruise fall into the same category. In essence, most of their customers would like a refund as well. I am sorry to be unsympathetic to your situation but you chose the terms of the cancellation at the time of cancellation and have since changed your mind. That is how the cruise line will see it.
If you do not agree with my perspective, you can always try to appeal to someone at Celebrity by asking for an exception to the rules. I would be straightforward and businesslike, accepting responsibility for changing your mind about taking a future cruise and beg for their mercy. Stating that you are "older" (didn't you know? 64 is the new 54!) and that you have many unexpected expenditures will not sway them as they have heard it all before from people who are much older than you and who may be in a dire financial situation. Here is the link to the company contacts at Celebrity:
www.elliott.org
Write to the execs one at at time, waiting
at least two weeks for a reply before moving to the next name on the list. Be patient. This is a very tough time to be running a travel-centric business.
One last thought......would you consider requesting an extension of the deadline? If so, you will have a better chance of getting that than receiving a refund.