To answer your last question (and be a little tongue-in-cheek) "how do you lose weight on an average American calorie intake?" - the long and short of it is: you don't. The number of Americans that are overweight is at an all time high. We're consuming evermore calories and it's generally not compatible with living healthy and losing weight.
Your thoughts to exercise more to up your intake are on track - I also originally felt my calorie intake was too low but by adding exercise I got a more comfortable range that didn't involve mood swings and general unpleasantness, LOL. On your MyFitness page, near the top is a button that says "change my fitness goals" (or something). From here you can change the amount of calories you burn on a weekly average, which will change your food calorie goals.
On the flip side of that: what are you eating? You say there's only about a 100 calorie difference between the top of your range and where you "normally" eat - is it possible to replace one snack or one component of a meal to get more within your range? And then you're not overhauling everything, you're making a small, single change. One oz of cheese, a tbsp of olive oil, these are about 100 calories. Can you cut that much?