Well, achieving a flatter stomach is all about reducing your overall body fat level.
What you are doing now sounds good. Its quite a lot of exercise, but if you are fit enough to do it then its ok.
I can offer a few ideas:
1. To target the fat stores directly, try doing unfueled cardios, i.e. cardio workout in the morning before breakfast. You dont have to do this (I for one dont), but its a tested technique which bodybuilders often use when cutting.
2. If you can/ want to, add some weight training. This helps preserve your muscle mass while losing weight, essentially protecting your metabolism from dropping. Weights are often underestimated in their contribution to the fat loss process. Again, its not mandatory, but it helps.
3. As far as specific exercises go, the more muscle groups you work the better. Training the abs is of course good, but you will get better results if you focus on your other major muscle groups as well. Things like squats, presses, rows, etc. are good exercises to incorporate if you have the time.
4. Watch your diet. This will make or break your efforts. I answered a pretty comprehensive weight loss question earlier today so I think its easiest just to link you to it: [Link](Mouse over link to see full location)
5. Remember to get plenty of rest, both in the form of at least 1 rest day per week as well as getting plenty of sleep at night.
(Old message)
I do want to add a few things. Getting a flatter stomach is all about weight loss. It can only be achieved with an overall reduction in body fat. Just so you are aware of how things work since most people think they can isolate from where to lose the fat.
The other thing is, if you are training your stomach, I would also recommend training your lower back. Training one side of your body only will lead to bad posture, which in turn will lead to back problems etc. In general its always a good idea to train agonist and antagonist muscle groups. Have a look at this article:
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