Breakfast - Used to have porridge, but stopped a few years ago as didn't feel great afterwards. Now usually just have a couple of slices of bread/marmalade with coffee.
Lunch - Soup and a sandwich or poached eggs on toast or a salad during the summer.
Dinner - The usual 3 veg with meat.
Between meal snacking a couple of biscuits with a coffee. Have stopped the biscuits since I started testing.
Very rarely drink alcohol.
Your breakfast has zero protein, your lunch has very little (soup and sandwich), 2 eggs have about 12 grams of protein. The coffee can set off BG issues especially without balanced meals.
So possibly by 5/6pm you've only had 15 grams of protein in a day. Your liver needs protein to clear toxins, and the liver is the main driver of glucose management in the body. Lunch you are also having bread (sandwich, or toast).
Bread makes me spike to high numbers (10+ often with bread), yet my hba1c is normal range. Root vegetables don't make me peak beyond 7 (soups are slightly worse than whole root veg, since the glucose hits the blood quicker), even if having 200grams in a sitting.
I'm sure people will suggest straightaway going low carb, but once you start this, it's very hard to come off, and leaves you nowhere to go.
I would suggest having more protein at breakfast and lunch (greek yogurt, cottage cheese, some meat), and swapping bread for some other slower digesting carb.
If this doesn't work, then you can go more to proper low carb.
For some reason, bread is the main culprit for me. Replacing coffee and biscuits with a small, mixed snack in the afternoon would help with balancing sugars, too.