Hi eissac,
Unfortunately, one of the most frustrating things about weight loss is when your records indicate that you're eating the amount of calories it would take to lose weight and it doesn't happen. With a daily caloric intake of 1500 calories, and burning 2800 all day, which gives you a caloric deficit of 1300 a day, you should be losing 2.5 pounds a week. With all your medical tests coming back negative, then you have to look carefully at the accuracy of the calorie intake because how could it be that you have a 1300/day deficit and not lose weight? Some people believe that some people will simply store more calories than other people. There's no convincing evidence of this, and there's no problem with your thyroid. The thing about weight loss is that to lose you must burn fewer calories than you consume, and that's true no matter how much exercise you do. Even if you run a marathon every day you will not lose weight if you consume more calories than you burn. So if you're not losing then the only possible explanation, given our current understanding of weight loss, is that you are consuming more calories than you burn, even if you think you're not. And I know this is maddening to hear, but in fact, research shows that people can under estimate their calorie intake by as much as 40% to 50%. Even dietitians miscalculate. Now, in some cases, people eat so few calories that their body senses starvation and slows down metabolism, but this doesn't look like what's happening in your case.
What I suggest that you do is check your basal or resting metabolic rate (BMR) here:
http://www.webmd.com/diet/healthtool-metabolism-calculatorAnd then to the exercise calorie counter here:
http://www.webmd.com/diet/healthtool-fitness-calorie-counterAnd here's the Food and Fitness Planner to estimate your calorie intake.
http://www.webmd.com/diet/food-fitness-planner/summaryGo ahead and add your BMR to your total exercise calories, then subtract that number from the number of calories you consume all day. If the number is negative then you'll lose weight. For instance, if you consume 1500 and burn 2000 with BMR and exercise, then you get -500 (minus 500), which means you will lose a pound a week (3500 calories equals one pound - so 7 days of a 500 calorie deficit = 3500, or one pound)
You can post your diet-related questions to the Diet Community:
http://exchanges.webmd.com/diet-exchangeAnd then you can select one of the Diet Clubs for support and information based on how much weight you want to lose.
http://exchanges.webmd.com/dieting-club-25-50-lbs-exchangehttp://exchanges.webmd.com/dieting-club-50-100-lbs-exchangehttp://exchanges.webmd.com/dieting-club-100-lbs-exchange If you do the math after keeping careful count of your calorie intake and estimate of calorie expenditure, and it still shows you should be losing weight, then please post back and let's see what we can do. And if you have any exercise questions feel free to post those too.
Take care, Rich