Welcome to the forum Irene, I’m sorry you are having to go through such a tough time.
Your experience points to long covid and diabetes is now being considered one of many long term conditions caused by covid. I’m curious as to whether they did a c-peptide test at the hospital? Your doctors could be assuming T2 based on age but there is a chance you have late onset diabetes brought on by covid. I’m speaking from experience here & a c-peptide test to measure insulin production was the only way I confirmed my diagnosis. T2’s have plenty of insulin but can’t process it where as T1’s produce low amounts & eventually none.
Low carb diets can help both types of diabetes. Less carbs mean less of a need for insulin from either your body or injected. Do you have anyone that can help you by cooking meals until you feel better?
Your exhaustion, fuzzy head, sore eyes could all be caused by your diabetes & lowering your numbers to between 4-7 would help. If you have to cook for yourself you could have a couple of go to meals that are low effort. For example eggs & bacon for breakfast, a salad for lunch, meat & veg for tea. You could also use an app to carb count & keep track of meals so you have less to hold in your mind.
If possible I would take more time off work as it does not sound like you are fit to go back.