I am 6 mos post-partum and I am almost back to my shape. I still need to loose about 5 more lbs, and some fat around my hips, but for the most part the stomach is flat and I am in good shape. I was closer to my pre-baby weight and size, but I injured myself and now need to have knee surgery so my cardio is limited to only walking. I don't always eat good (yes I eat pizza) so I think if I cut that out I would loose this last bit. I don't know how much weight you gained, but I only gained 27 lbs so I did not really have that much to loose.
IMO if you are eating well and still not getting to where you want to be I personally would do more cardio at least 5-6 days per week for about 45-60 mins. I also highly recommend bootcamp. I too still have a little roll, but I have talked to many other mom's and a lot have said it does really start to go away more at about 8-9 months. Give it more time, I think it will go away. Remember what the Dr always said "you did not gain it over night, you won't loose it over night!".
I hope that helps! Hang in there!
Good Luck!
Jana