There are also other medical issues that can cause weight gain/retention. You might want to talk to your doctor about that. In addition, there are a lot of instances where a person can have "normal" thyroid levels (meaning they fall in between the numbers), but may not necessarily be normal for you. Another possibility to check out.
That said - I agree with gokuangel about keeping a food journal. You need to calculate the number of calories you need each day to maintain your weight, then eliminate enough calories to create a deficit. Quite often, we end up eating more than we think we are, so writing it down will allow you to keep very close tabs on it. Eat a wide variety of foods and vary your calorie intake a bit once in a while (more one day, less another day).
Also make sure you get balanced amounts of all different types of exercise, cardio, strength, etc. Also vary the routine from day to day because if your body gets used to the same routine, it will know what to expect and your work out will no longer be a challenge.
Good luck and hope to see you around often.
Are you keeping a food journal? if everything comes bk normal then i would suggest the journal! Spark people is free and you can count your food and it even has suggest meal plans!!!