Honestly that doesn't look like 1400 calories to me. Are you sure that's all you're eating? Also, I gotta say that's NOT a healthy eating plan by any stretch of the imagination.
Just some thoughts:
Breakfast- 1 1/4 cups honey nut cheerios
This is not a great breakfast. It's all carbs, it's all sugar, and there's nothing there to keep you full throughout the morning. It's also got a lot of sodium in it. Why not have something healthier and include some fruit in it. Oats, yogurt, eggs, a smoothie of some kind ... anything you can add fruits or veggies to.
Totally wasted calories. All carbs and sugar. Have an apple and some cheese instead.
Lunch- PB & J (nibbling on the kids crusts. I gotta cut that one)
There's nothing wrong with PBJ but what about a piece of fruit or some chopped veggies to go with that?
Snack- whole wheat crackers
Carbs and .. um .. carbs. And sodium. Lots of sodium. What about chopped veggies. Or a boiled egg and some veggie juice. Or something like that.
Dinner- half a chicken breast, frozen veggies, brown rice (1/2 cup)
Honestly I'd say this is probably the only truly healthy thing you're eating all day. It's balanced and healthy.
But the other thing is that there are no healthy fats that I can see. You NEED to make sure that 20%-30% of your diet is healthy fats. Without those fats, there are other vitamins and minerals that your body can metabolise.
It's not just about calories - it's about the RIGHT calories. You need more fats, more veggies, and less carbs in your plan. And probably less sodium - which is probably causing a bit of your weight fluctuation.
After dinner- I'd probably have about 250 worth of stuff