How do I increase my daily calorie intake while staying under 20g of carbs?

I've been keto since January 5, 2016 and lost 48 pounds. I was eating under 20g of carbs, had some slight slip ups, didn't exercise and was unintentionally eating low calories (500-900). I can't get myself to eat 1200+ calories because I don't feel hungry and I'm busy with school and other academic activities. What foods do you recommend me trying out to fix my calorie deficit?