Welcome! Many of us find that adding in 8 hours of sleep to our daily activities puts the calorie burn more into line with reality (even though 8 hours of sleep is supposedly already figured into the calculation). You may have to adjust your activity level up or down as everyone is different and at best these calculations are an informed guesstimate.
1200 cals does seem low at your weight, but if you can stick with it you should see some quick results. The big problem is that you may find yourself getting too hungry and thus more prone to give up or "cheat". You might think about, say, 1500 cals which should still give you around a 2lbs. a week loss. I would also suggest you include plenty of protien--I personally try to keep about a 40/30/30 carb/fat/protien mix but again, do what works best for you.
47 M 5'8"
May 4, 2010...... 440? lbs. (Start FitDay Size 60 Jeans)
June 19, 2010.... 393 lbs. (First Weigh-in)
June 19, 2011.... 229 lbs. (164 lbs. gone in one year :-)
Current Weight... 185 lbs. (Size 36 Jeans)
Next Goal 169 lbs. (07/04/12)
Ultimate Goal 165 lbs. (12/31/12)
The best exercises for weight loss are Fork Putdowns and Table Pushaways.