calories i need to maintain my weight

I've lost enough weight now I believe,, 5'8 height 135 pounds in weight and i am 19 years old.
Now, I am not sure whether I am sedentary or lightly active.
I am a boarding school boy so I have to walk to lessons, lunch, supper and I normally play badminton for around 3-5 hours weekly. I do weight lifting (30 min sessions) 3-4 sessions a week. I occasionally go into town (walking) for an hour or two.
I am tempted to go for 1900 calories daily but is that to much?? I just dont want to gain back any weight.