Eating too much?

Hello everyone!

I've read a lot about that if you want to lose some weight, you need to eat less calories a day than you burn. So I got my first fitness tracker (FitBit) this Christmas, and now I see how much calories I burn a day. I've set a meal plan as well to keep my calorie intake 500 kcals less than I burn. It works pretty well, I already lost 1 kg since Christmas so it seems to be working.

The problem is that now I have to study a lot cause I have exams in uni, and I usually just sit at home all day, do yoga in the mornings, and a workout in the afternoon, still I burn very few calories a day, so my FitBit says these days I shouldn't eat more than ~1000 kcals a day... I think it's too low and rather unhealthy. I'm more used to eat 1500 kcals, and I feel fine with that. I can't be more active cause I won't have enough time to study... :( What should I do? I don't want to starve myself but don't want to gain weight either. Any ideas?