I would go easy on milk as it contains about 5% sugar. I used to love porridge with milk but find the milk quite as problematic as the starch in the oats bg wise so stay off both most of the time. Cream is also comparably high in carbs but you wouldn't use the same amounts usually.
Mayonnaise, olive oil, coconut oil, duck fat, goose fat and other lovely fats lack carbs and will fill you up nicely.
Fats don't make you fat, they fill you up and make you stay full for a long time.