Mimi, another thing you can do is to get out of bed in the morning without using your hands.
If you hoist yourself up using only your lower abs, you should be able to really strengthen the abdominal walls, and in conjunction with your cardio, should start seeing a 6 pack real soon.
When I had my waterbed, I had to really work the ab muscles just to sit up. I had a wicked 6 pack.
Sadly, ...that was X number of years ago, ...and they are slowly disappearing.