That sounds about right to me, but all of those calculators are merely estimates. The point is, most forms of exercise, while important for weight loss and health, burn a depressingly low number of calories. That's why diet and portion control generally contribute more to weight loss than exercise.
It sounds like you have a pretty good exercise program going already. It would probably be better to stick with that (assuming you're losing weight)
than stress over fitting in more exercise. You might, however, look into some alternative forms of exercise that burn calories more quickly (e.g., running and cycling). But, those higher intensity exercises can also cause more injuries if you're not careful.
Anyway, don't stress over the exact calories burned number - your weight will tell you if your diet and exercise program is successful.
http://www.WeightWare.com
Your Weight and Health Diary