Add cardio to your workout. Walk fast, jog, get on a bike, anything to get your heart rate up. Cardio burns fat, it will kick start your metabolism and get it going. Do at least 30 minutes of it most days of the week. Lift weights when you are watching TV, walk around the block 3 times a day, do squats when you brush your teeth, just keep moving.
CAn you elaberate more on your current condition with your thyroid? and your meds?