Try yogurt and blueberries for breakfast. That will be your "high carb" meal of the day but if you're going to eat carbs, best have them in the morning where you will have opportunity to burn them off. Actually, these are "high quality" carbs and not that bad for you. Figure about 23g in yogurt and about 13g in a half-pint of blueberries (after the fiber is subtracted).
For lunch, have a tin of sardines packed in olive oil and a few wedges of cheese, or perhaps, an ounce of nuts (peanuts, cashews, pistachios, macadamias, etc.).
Dinner, have a plate of your favorite fresh fish or seafood. Or make a salad that has plenty of vegetables and sprinkle cheese and nuts on top. Have lots of olive oil (instead of dressing). Have some blueberries, strawberries, blackberries, raspberries. All berries are good for you on a low-carb diet, even though they have carbs, they are high quality carbs. I make a salad at home every night now and I am becoming a real cheese gourmet. I have tried out at least a few dozen types of cheeses over the past few months that I put over my salads.
Now I also put bacon bits or chicken or diced eggs in my salads but you say you can't eat that stuff. In your case, experiment! Try some exotic nuts and cheeses and add more types of vegetables, for example. Most importantly, use plenty of olive oil. It's high in the good kinds of fat and will help make up for the fact that you don't eat meat and eggs.
What is with you and sardines!?!?!?!? Do you own a sardine canning factory? lol!!!
Mark