You don’t have to predict what you are going to eat all day - only your next meal. And if you fancy an extra roastie or a pud, you can give yourself more insulin. There is not maximum number of doses you can have in an day.
When you start carb counting you will soon get to know what is worth counting and what you can “ignore” - you don’t have to be super accurate. The carbs in the flour you use for thickening your gravy will probably be lost in the carbs in the potatoes or the fruit crumble and custard.
You can eat when you want. If you want breakfast at 3pm, have breakfast at 3pm as long as you have your insulin. If you don’t fancy any breakfast, don’t have it and don’t take insulin for it.
If you get it wrong, correct (treat the hypo or give yourself more insulin) and learn for next time. I am pretty sure everyone with Type 1 has made a mistake at some point but there are lots of us here to tell the tale.
I appreciate how daunting it feels. Think of it as grieving - you can cry, you can get annoyed, you can feel frustrated. We have all been there.