Abs are made in the kitchen!!
After reviewing your diet, it appears to be very low in protein and high in simple carbohydrates. You should be taking in your body weight in grams of protein. It goes without saying that the protein you consume should be lean protein (chicken breast, fish, etc). Also, add more complex carbohydrates (broccoli, potatoes, brown rice, etc) to your diet which will inhibit the rapid release of insulin. An easy to understand diet can be found on the Body for Life website.
Also, you may need to increase your calories. This may seem to be counter intuitive, but the muscle you have built requires more nutrients to keep from catabolizing.
There are so many factors that can help you lose the fat around your stomach (timing of your meals, macronutreints, etc.) If you really want a defined stomach, I would suggest looking at the bodybuilding.com website.
Hope this helps!!