What can be done to fix the uneven stomach I'm left with? Is this result from a mistake made by my doctor? (Photos)

this is very unfortunate to improve this if AT ALL you will need to start RF treatments with shock therapy at least 1-2 x a week in the office, once the skin starts to improve then you will need a tummy tuck with fat grafting to get some improvement.  internal heating is NOT the answer for this but maybe used with surgery to improve.  I suggest you see a revision expert.
You need a formal evaluation by an expert in body shaping and contouring to determine what is best.  Traditional liposuction awake and smart liposuction are old methods and do very poorly for tightening skin or significant skin tightening or contouring.  Small problem areas can be improved slightly by these methods.  The best in body contouring not only removes fat with energy devices like VASER ultrasound but also internally heat the skin with radio-frequency devices such as J PLASMA/RENUVION, InMode BodyTite, ThermiRF to heat the under surface of the skin and tighten it at the same time as fat removal. These combinations are called 4D HIDEF VASER contouring and can only be done by a well . trained body contouring specialist. At the same time fat should be harvested, PRP and stem cells added and injected into muscles or indentations/cellulite to get body shaping and contouring.  This is known as a Brazilian butt lift when you inject the fat to the buttock for contouring and lifting, but fat can also be used in areas such as the chest/breast, arms/shoulders, calves and face.  Cellulite should also be treated with cellfina, sculptra, subcision and/or fillers such as bellafill, renuva synthetic fat, or sculptra.  If skin is very loose before surgery then it will need to be removed such as lower abdominal skin (tummy tuck/abdominoplasty), breast skin (breast lift), arm skin (brachioplasty).  Overall you need a full assessment, but simple liposuction alone will not tighten skin and needs a combination of various methods -- fat removal, skin tightening, defining, fat grafting, skin removal -- to get the best in body contouring and body sculpting.  Dr. Emer.

BodyTite is a radiofrequency skin tightening and fat shrinking treatment that really helps when there is uneven irregular spots after lipo.

External radiofrequency treatments could be helpful. Also, Sculptra injections could be helpful to help fill in the dents or fat transfers.

What you need to do to correct this deformity is to tighten your skin with a pubic skin resection and utilize VASER liposuction and microfat grafting by a contouring master. If you choose the appropriate surgeon, you can have your concern corrected effectively. The definitive correction for liposuction deformities requires the advanced technology of ultrasound assisted VASER liposuction. As an official trainer of VASER liposuction, I encounter suboptimal liposuction outcome referrals weekly. VASER liposuction has been the only modality that has consistently corrected liposuction caused deformities. VASER liposuction ensures a smooth contour regardless of severity of contour irregularities by virtue of being able to remove any and all remaining fat comprehensively and uniformly. Finally, when skin redundancy irregularities are observed, Renuvion technology can be simultaneously applied to tighten your skin to optimize your overall contour outcome. A Skype or FaceTime consultation with a VASER specialist will help you get an accurate recommendation and pricing. 
Respectfully, 
Arian Mowlavi MD, FACS
Realself 100 Hall of Fame Inductee