Should I be doing more weight training?

I have been working out for the past three months 6 days a week. I do cardio all 6 days. 2 out of the 6 days I do a full hour (burn about 550-600 calories), the other four days I do 40 minutes of cardio (burn about 400-450 calories) and then do fitness on request. (Either More Core, Conditioning 35, Upper body, Legs, muscle drills) I have not lost a pound. I do think I may have lost some inches and toned but I would really like to drop the weight. I am very good about logging what I eat to be exact and stay within my calories that I need to eat in a day. (1200-1500 calories) What I am wondering is, should I be cutting back on my cardio like three days a week for 45 min. and the other 3 days do a warm up for 5-10 minutes and then do weights for the full hour? I am not sure what I am doing wrong since I am not lowering the numbers on the scale. Can I get some help from a personal trainer on this issue? Please and thanks.