I don't know a lot about thyroid disorders but I do know that they can play havoc with your weight loss plan. Your exercise is good, for more than just weight loss, for overall health.
I suggest you start to track your food intake. There are several good free sites online where you can track your food and see how many calories you are eating, how much fat, carb, protein, fiber etc you are taking in. This is one place to start. Some of these are Fitday.com, Myfitnesspal, MyPlate just to name a few. There are also sites online that give you an idea of how much you should eat based on your age and height, and body structure. Concentrate on eating foods that have a high nutritional value, and eliminate empty calories.
Look around this forum. There is a lot of information from people who have been in your position. The best information you can get is from those who have already done it. Find out what can work for you long term.
Good luck to you.
If I had started this a year ago I would be at goal today!
First Goal - 199 Onederland!
Second Goal - 180
Final Goal - 150