It actually sounds to me that u r eating too few calories for the amount of exercise u r doing. With all that cardio you need to make sure that you are eating enough, especially carbs, so that your body doesn't end up cannibalizing your lean muscle tissue for fuel during your long workouts. The weight loss you have achieved so far is awesome, but what happens when you eat too little is that your metabolism slows down, which means the last pounds will be a lot harder to lose. In order to increase your metabolism you need to be preserving and building lean muscle tissue, which uses a lot more calories even at rest. So continually up your weights during your Jillian workouts and perhaps even consider replacing some of the second cardios with proper weight training. There are some awesome weight training dvds for women, some of my favorite instructors are Cathe Friedrich, Jari Love, and even Jackie Warner. I know that the Jillian workouts use weights, but they are lighter weights with higher reps for cardio endurance so you won't actually as much muscle as you would if you use a proper weight training dvd.
And don't worry you won't bulk up. Women don't have enough testosterone to get bulky. Muscle actually takes up a lot less space than fat, so if you are replacing your fat with muscle you are actually going to look smaller even though you might not notice a huge decrease in the scales.
The other big key, if you are not already doing it, is to eat protein with each meal so that you are feeding your muscles. A good low calorie protein shake after your workouts is a must! The best brand i have come across is Matrix - they have some awesome flavors.
Good luck!