What's your daily caloric total? No breakfast plus just veg for lunch sounds like you're on an extremely low calorie diet, which will work for just about anyone regardless of if it's keto or not.
Such as eating baked cheese, adding extra butter (any fat) to meals. Avocado is a great fat-packed vege. Lots of cream cheese..
1/4 cup of guacamole (depending what you added) is about 4 grams of carbs, probably affordable.
Both are about 100 calories.
For a quick snacky lunch, I love celery and cream cheese or, depending on what mood I'm in, celery and mayo.
The result is the same for you, but that does mean there's other ways to get to the goal than the keto diet. (which is good news for everyone)