Hypothyroid Help!!!! Need to lose weight...?

Hi. I am a 23 year old female, 5'4" tall and weigh 160lbs. In 2007 I was 100lbs until I suddenly started gaining a lot of weight (~30 lbs in 2 1/2 months). I was diagnosed with hypothyroidism later that year (initial TSH was 14). I am currently taking 50mcg Synthroid (one in the morning) together with 30mg Armour twice a day. I am also taking Metformin (2 500mg in the evening for PCOS) and Citalopram. I eat approximately 1400 calories a day (mostly lean protein and low glycemic carbs) and work out for 1hr 15min four to six times a week. I am still gaining almost a pound a week ( my body fat percentage is increasing). What do I need to do to start losing weight?