Why is my stomach not flat after a mini tummy tuck?

It looks like your upper abdominal skin is thicker than the lower. You might benefit from liposuction and scar revision as the scar appears tethered. Flatness is frequently achieved through tightening the muscles but you have a poor transition from the upper to lower areas related to the scar.

It's difficult to say what occurred without an examination or pre op photos. From the provided photos it appears you are a better candidate for a standard tummy tuck versus the mini. Swelling should be resolved at six months post op. I encourage you to return to your surgeon for an evaluation and discussion of your concerns.

Dear non flatto,
I understand your concern. However, without a proper assessment it would be difficult to determine what is wrong. It is best that you visit your plastic surgeon for further assessment. Only after thorough examination you can get proper recommendations and advice.
Daniel Barrett, MD

Excess fat after a mini TT often occurs when insufficient or no liposuction was performed during the procedure.  After 6 months of healing, a TT revision with lipo can be considered.  The key to an uneven scar is how the tension is managed at the end of the operation. 
Kenneth Hughes, MD, ABPS Board Certified Plastic Surgeon
Los Angeles, CA

Hello and thank you for the question and sharing your photos. There is an area of loose skin above your tummy tuck scar. You will benefit from a revision procedure to remove the excess skin. You should discuss your concerns with your plastic surgeon. Best,