Thats the tricky thing about numbers, and if you only want to lose 5 pounds then it seems more like a vanity issue because of what the scale says. I am 5'7" and weigh 148, with a body fat of 17%. The more muscle you have, the more you will weigh....so 141 for someone 5'9" is a normal weight, unless it's all fat. The more muscle, the leaner (despite the numbers on the scale). I am shorter, weigh more, and at the same time wear a size 4 jean. In order to break your plateau, determine your body fat first. There is a simple way to do that to approximate it. Your weight is constant because you are not burning any more calories than you are taking in. Judging by your minimal diet, this is a result of not enough exercise and a slowed metabolism.
Increase your exercise & eat 6 small meals a day (low cal, unprocessed) in order to speed up your metabolism.
If you are not planning on doing cardio, then your ab workouts will be futile because you will never burn the fat that covers them. Kickboxing, taebo, running- Any cardio provides cardiovascular benefits, but in order to blast that fat, keep that heart rate up at least 90 minutes 3 times a week.