I'm guessing you're trying to lose fat. That is too much cardio to tell you the truth, you don't really need to do anything more than 20 minutes if you're doing it at a somewhat respectable pace. As you probably already know, what you put in your mouth is most important when it comes to losing fat (notice I say fat and not weight). 85% what you eat, 10% weight training, and 5% cardio is how I like to break it down. Of course you are going to have to ramp up some form of cardio when you get into the lower bodyfat percentages to shed those last few pounds of fat, but most people are not and will not ever be at that level.
My wife weighs 145lbs and is 5'7 and she cuts fat eating 1800 calories and it's very effective. She trains with me 5 nights a week and she does cardio only on the weekends for 15 minutes which consists of running hills. I would bump your intake up to atleast 1500 and monitor that for a while and see how your body reacts to that because if you drop too low your body will panick, and hold onto the fat and not get rid of it like you want.
Also, do yourself a favor and throw away the scale. Take measurements with a tape measure and go off of that and the mirror. Or you can just go by how your clothing fits. The scale can give you the wrong idea and can really bum you out considering how much weight fluctuates throughout the day. If you HAVE to have a scale... take measurements once a week, in the morning after you use the restroom.
If you want me to I can go into much more detail about what to eat and all of that jazz I'll be glad to help out.