Roughest part of the day - making lunches

Anyone else find it tough when making the kiddies lunches, just got muching away on Cheez-it crackers, just to find out I ate roughly 400 calories on a couple of handfuls :-(. I don't have an HRM so I'm also finding it hard to keep track of my calories burned while excercising, I'm never sure if I am going over or under when logging them, so after eating a few handfuls, I'm now over on my calorie intake for the day, so discouraging at times!