For your age you need 2000-2300 calories per day. Some suggestions for high nutrient foods which are quick are nutrient dense drinks which can be store bought and made from home, such as Yogurt smoothies, milkshakes, and Carnation Instant Breakfast (drink at anytime, not just in the morning). Any food combo with protein (cheeses, yogurt, or meat) and starch (bread, pasta, rice, fruit, or vegetables) such as Yogurt mixed with fruit and nuts or seeds (adds protein and more calories), cheese/chicken enchilada, or pizza are high nutrient food, quick, and easy to eat.
You know, it wasn't 'til this past year that I discovered that my own dizziness comes mainly from what are called silent migraines. Do you ever have bad headaches several times a month? Did you know migraines are more than really bad headaches and that you can have a migraine without having the actual headache itself? Dizziness and fatigue are big symptoms.