Re book for March

[MENTALMUM]

Just had my December flights cancelled and looking to change to March, anyone been brave enough to do this or do you think it is a bit to soon.
I have the dilemma that I have had to change all this years holidays to next year. I have changed three to next year already ( not all Florida). My place of work ( NHS) will not allow me to carry holidays over and we are expected to take them in this current financial year, this leaves me with having to rebook by the end of March or not being able to go back until after April 2022.
I am in a quandary and have a couple of concerns about booking for march, will I still be able to rebook for free if they are not flying in March? and never having been at this time of year not sure what the weather would be like, we normally travel at the end of the year.
I have been on my booking and cancelling is not an option only an open ticket to rebook.
Any advice would be great, thanks.