Well I'm sure you know that breast feeding is good for weight loss, and I'm sure having twins increases it's effectiveness. Your other issue may be the switching back and forth between diets and exercise routines. All these changes can affect your body and it can take longer to see results because your body needs time to adjust to what you are doing. Also a breakdown of what foods you are eating will help. Calories are not created equal. Just keep it simple with your food and exercise and results will come. Try taking measurements instead of weight also.