I missed you! I think you were one of the only people who agreed with me that fishball noodles could be a great pre-race meal! Welcome back! I'm still in Vietnam and still eating noodles.... I hear you about how demotivating getting sick is. I got the flu two days before my second HIM (Vietnam in 2015). Did the race anyway, but nowhere near what I was capable of, and came very close to quitting the sport in frustration over my crappy luck. (It was far from the first time I'd gotten sick before a big race.) Ended up getting a coach who has at least partly helped me figure out my issues with overtraining and taper (and.....ugh....the bike) and ended up qualifying for 70.3 Worlds last year.
Set a goal ("maintenance" isn't that motivating!) and take it step by step.....it'll come back!