You can't multiply the BMR for "light activity" and then also try to figure in the exercise. One or the other. The light activity IS your exercise level.
Try Spark's way - multiply BMR only by 1.2 to account for day to day non-exercise work. Then add in your averaged weekly exercise (288).
Then, as the PP said, you're already at a normal weight for your height. If you do have fat to lose at all, you will lose it slowly and should not aim for more than half a pound a week. A full pound is only suitable if you're actually overweight. So you'd only subtract 250.
+288 = 2083
- 250 = 1883
So you should be eating somewhere around 1600-1950 or so daily.
By taking in 1200, you're creating a daily deficit of 880 calories - which is far too high for someone who is not actually overweight. Your body's response will more likely be to stop losing weight, than to lose it.
Deb, in New Zealand