I agree with Rachel that it's fat loss that will make the big difference for you. You don't mention your diet, so that's probably the most logical place to start.
It's great that you're exercising and getting to work on your bicycle. If you haven't been taking your body measurments, make sure you start. Perhaps you're losing inches elsewhere right now and eventually you'll start to see some losses in the tummy. (My stubborn spot are my hips and thighs, and I lose them last.)
Another possibility is something I've read before about swimming. It's a great exercise, but I've read that it's not the best for fat loss. There are other aerobic exercises (like walking, jogging, spinning, aerobic dance) that are better for overall fat loss - especially when combined with strength training.
Hope this helps a bit.