Do you work out every day or something? I have a stupidly fast metabolism and I only eat about 2,500 kcals a day (on a good day) and I've been slowly growing for a while. Do you increase weight on your workouts and everything?

The best way to do it is eat like 6 relatively small meals throughout the day, or 3 full meals and 3 calorie/protein packed snacks + a protein drink.