What does 'medically controlled' mean when you describe your diet? If you are still making your food choices yourself, and cooking and buying food, then take a day or two and just eat some frozen meals and have some liquid meal supplement to add up to 1500 calories for the day. Don't eat anything else and don't snack. Do that for a few days and you should lose weight. If you don't, then you should go straight to your doctor and explain the situation.
If you don't lose weight when other people (companies, products) are doing the measuring, then you have a medical problem and your doctor should become involved in working on THAT problem. When people measure food for themselves, and start tracking food themselves, errors start to creep in. A few days of frozen meals will show it.