The best way to experiment is to watch both the scale and the tape measure. The scale shows your weight change in pounds and the tape measure tells whether the pound changes are fat loss and muscle gain.

If you add exercise, are you okay with seeing your "weight" not go down as fast?
for example, what if one week, you lose 1 pound of fat, and gain .5 pound of muscle. That would look like "losing .5 pound."

if you add exercise, you can still have a 400 calorie deficit. Say you averaged 300 calories of exercise a day using those charts available all over the net.
then you could eat 1800 calories and still have your 400 calorie deficit and get whatever goodness you're already getting. sounds like fun eh?

Personally, calorie counting doesn't compute for me. You have to make sure the calculator you use covers your situation. Many used in the fitness world were derived based on metabolisms of college guys, that are not insulin resistant, plus a standard higher carb diet - feh. But, it is a place to start if that's the sort of thing you like.