Need some advice.

I am 138 pounds. My goal is to be down to about 130 or a little less for January 6th, 2008 for my friends wedding in Mexico. I work as a night cleaner at a high school. I eat breakfast, workout, eat lunch, start work, eat supper then I have a snack at my coffee break. But when I get off work @ 11p.m. I am starving! Is there anything I can do to adjust my eating habbits, where I am not over eating but can still lose the weight by January? I constantly worry about food! Help!