I know where you're coming from. I work 12.5 hour (sometimes longer) ER shifts, oftentimes without any lunch or dinner break at all. I usually do the typical handful of beef jerky, protein bar or peel a few hard boiled eggs and eat the egg whites thing while standing in the corner as my "dinner".
You can get yourself a soft cooler type of bag and put convenient mini meals/food in there, such as cottage cheese, chicken salads (chicken breast, flax seed oil, chopped onion/celery), tuna salad, hard boiled eggs, raw vegetables/homemade dips (pureed cottage cheese, chives, garlic), sugar free yogurts with a portion of Metabolic Drive (portioned out into small baggies) and sprinkle of nuts or seeds (flax or sunflower)....or preportioned meals, if you have access to a microwave (my college had a micro by my class by a vending machine that sold hot pockets and stuff).
I've even kept those vacuum packs of tuna in my locker for a quick meal, just eat it out of the pouch, but those can be expensive. Anyway, these are some ideas of things that can be consumed when you're short on time.