Problems loosing weight?

Ok so i have gained close to 100 lbs post pregnancy. Now Im tryin to get it off. By not eating fast food almost 100 oz of water daily, walkin two miles 4 days a wk, NO white carbs ( rice, potatoes, bread, etc) and not eatin after 6:30pm. What else should I b doing in order to achieve a weight loss of 30 lbs by January. Any suggestions