You should eat a breakfast, and have that snack before bed like you were doing.
That way if headaches occur again, you will know it isn't from undereating, and consult with your doctor. It could be a medical issue related to your surgery, not anything at all to do with your diet.
Russell - current BMI 28.6
197 - bmi 30 - done
164 - bmi-25
| current weight: 183.4