Blood sugar drops below 3.0-4.0 mmol/l every time after eating healthy foods. Only way to keep it at 6 is eat at least 150-200g of carbs. Non-diabetic?

why keep it at 6? I have no idea why you want to keep it at 6. A level of 4 (or 72 mg/dl) is perfectly healthy and should not cause any symptoms. Some people will get symptoms below 3.3. It is a bit unusual but not dangerous to have levels that low. No problem eating that much carbs but still avoid sugars and starches; choose complex carbs. Consider seeing an endocrinologist and checking your Insulin levels.