Low counts?

This is my first week doing this, and I must say it's been a lot easier than I anticipated.

My target calories per day has been 1600. However I've noticed the past couple days it's been pretty difficult for me to get above 1200, even though I have been eating when I've been hungry, and felt full and satisfied afterwords, with no desire to eat any more.

For instance, today I had:

Breakfast: Yogurt and a Vitamin Water

Lunch: Baked chicken breast with broccoli and rice

Mid-day Snack: Fresh apple

Dinner: 1/2 chicken breast sandwich with mozzarella, lettuce, tomato, mayo, on hi-fiber whole grain bread. (Which, right now as I sit here, I feel like I overate).

My totals came up just a little over 1100. I figure I will have some cashews later after my workout to get my sodium levels up, but I'll still be sitting at only 1200 calories for the day.

I know it may be okay for it to happen every so often, but three or four days in a row? The first couple days I had difficulties staying UNDER 1600 - primarially because I had been eating a lot of pasta, which left me hungry later. But with all the fiber and protein I've been substituting, I'm feeling stuffed way under my count.  Ideas?