I am sorry to hear about the problem you are experiencing. My concern, based on your description and pictures, would be that the abdominal wall laxity that you are experiencing is now more obvious since the tummy tuck operation. Frankly, this occurrence is one of the reasons why I believe most patients who had pregnancies and/or weight gain/loss are not a candidate for mini tummy tuck surgery. At this point, your plastic surgeon will be in the best position to advise you more specifically. Best wishes.
Looking at your before and after pictures. It appears that the muscles are not approximated. This can be because of the suture line along the muscles breaking or pulling through the muscles, but more likely the muscles were not approximated at the time of surgery. Many surgeons do not suture the muscles as part of the "mini"tummy tuck procedure, but reserve that for a full tummy tuck. A more flat abdominal profile is typically achieved with the muscle plication. A similar picture is frequently seen when an abdominal muscle closure is performed only up to the belly button. In this case there is commonly a bulge above the belly button, and a flattened tummy below the belly button. Talk to your surgeon to find out what was done regarding the muscles. Good Luck.
Based on the picture, I don't see any evidence of muscle repair. If you had mini tummy tuck, you likely just had skin excision and some lipo. I don't see any muscle definition. If you had a true muscle repair, your abdomen / tummy would be much flatter and you would not have the bulge that you see which extends from your pubis to your chest. I would clarify with your surgeon if you had a muscle repair and if so, how high the repair extended.