If your blood sugar really is an issue (and I totally agree with PP saying you should get this checked out properly by your GP), then this is how I'd suggest you change your diet:
Breakfast - one cup of coffee, no sugar plus one banana
You need more protein and fat (generally), so I'd suggest that you replace this with full fat Greek yoghurt, with a small handful of berries or nuts/seeds. Or, eggs - boiled, scrambled, fried - make a good breakfast.
Lunch - fruit and vegetables and water
Salad, with some kind of protein element, so tuna mayo (full fat mayo), cheese, chicken pieces - with other veg in the salad like cucumber, celery, peppers. And an oil-based dressing (home-made, so you know it doesn't have any added sugar
Dinner - large portion of pasta / curry / fish etc.
Ditch the pasta (and rice if you're having curry. Have your fish/meat with vegetables instead - but avoid potatoes.
Cake is eaten after dinner daily.
Definitely ditch this!