Need advice

Imy 5'7 I weigh 137 pounds I want to get down to my goal weight of 117 I have been eating healthy food but I work about 70 hours a week as a bartender so a lot of the time I only have time for one meal a day I can't seem to lose any weight I go up a pound and down a pound but I always stay about the same I don't know what I can do to try and lose this extra weight I'm getting frustrated and I really need advice. A normal meal for me is steamed veggies such as broccoli and colliflower and boiled chicken. My breakfast everyday is instant coffee with *kitten* free coffee mate vanilla cream I can't survive without coffee I have two cups every morning and about 2 cups while at work to stay awake till 3 am I'm on my feet all day at work for my 14 hour shift and every morning when I wake up I do about 40 crunches and 20 pushup if anyone has any advice on what I can do to start really losing weight I could really use your help. I'm going on my first vacation in 5 years in may and I want to try to lose these 20 pounds by then .