Although you posted your first question last year, I can answer it for you. Why are you only loosing x amount of fat when you do loads and loads of stuff at the gym? Because you are using the wrong muscle fibres. But do remember that you should only really want to loose around 1-3lbs of fat a week, anymore than this and it could be potentially dangerous. Only a doctor could make that decision for an individual however, so a visit to the GP would be necessary.
But anyway, you have different types of muscle fibres in your body, each of which use a different source of energy. There are muscle fibres which use stored fat as energy, and it is these fibres you need to be using to burn fat. And the only way to use these fibres is with LOW intensity exercise.
It's quite plausible that if you've been doing those miles on the treadmill at quite a quick pace (jogging or running) then you are in fact improving your cardiovascular system (heart and lungs efficiency at delivering oxygen to muscles) and not burning fat. The "calories" part of the cardio machines is NOT fat! Those calories can be fat or they can simply be glucose (the fuel your body prefers for high intensity exercise) which are made by you body using mostly carbohydrates.
All in all, I suggest you briskly walk on the treadmill and leave out the weights for a different day separate from the cardio, or if not possible or you just don't want to bother with different days for resistance training, do them after the cardio session. And don't decide on how well you've done based on the number under the "calories" part of the machine!! A brisk walk for 30-40 minutes 3-4 times a week is fantastic!
It's not about going as fast as you can, as hard as you can! It's about keeping your heart rate high enough to be burning fat, and low enough not to be using other muscle fibres and using other energy sources.
Good luck and all the best! If any of the above is confusing, do say and I'll try to explain further. Good on you for going to the gym!! I can imagine it's hard for people who have excess fat and want to loose it to go to the gym and keep it up.