I tend to agree with @Jolyzara take a look at your past breaks and it sounds like you did not take a proper recovery from your sickness and started back too soon (when unless you are racing CX why?).
I’d take a solid 1 week off at the start of the new year and then build your FTP and confidence.
Leadville is a ways away and you already had solid fitness base going into it (300+ FTP is admirable for most). If your goal is sub-9 you want a good base training season and not burn yourself out early.