My mother had tummy tuck surgery and she was very satisfied and her stomach was totaly flat. So you should ask your surgeon about this because as far as I know your stomach must be flat after this surgery.
What was the reason for this surgery? Did you have problems with weight or something else was the reason? And how was everything? Surgeon, clinic and price?
And since it has been 7 months after your surgery have you been at check up? Did you talk to your surgeon about your concerns?
If you are worried maybe you should seek second opinion. My mother said that after she had recovered she didn't have any problems. And her stomach was flat right after the surgery. And she mentioned that she was strictly following the instructions the doctor gave her.
Hopefuly you will resolve your problem in a positive way and that everything is going to be fine.