I had this problem some time ago.
First of all,you have to learn how to cook,mums not gonna be there forever.
The way i use to consume so much food during work hours was taking food you could eat on the run.Another way was to break down food so you have twice as many calories in smaller meals.
Some examples are:
I would mix crush almonds,pumpkin seeds,flax seeds,oats,pecan nuts,walnuts and protein powder into a bowl of all natural yogurt.This would bring up the calories,protein,carbs and fats of the same size meal incredibly.
Another way was instead of being able to eat 6 whole eggs in one sitting,whisk them into your protein shake before work.Sure it's not as enjoyable but your getting no less,if anything more nutritional value from the raw eggs then if they were cooked.
whole meal sanwhiches with chicken breast and cottage cheese were great to eat on the run.
All kinds of nuts you can pick at through the day.
Thats just some examples so you get the idea.
All the best