How to achieve a rounder butt in bottom area?

Adding more fat on the lower area of the buttock will not resolve the problem, I think that you reached the result that you can get with the fat transfer procedure to remodel and reshape the lower back contour and buttock and only a skin resection can remove can resolve this problem.

Hello dear!
Thanks for the question and provided information as well.
Based on your pictures, you are a good candidate for liposuction with BBL, to reshape your buttock, and give you a beautiful heart shape.
In general, you need to be physically healthy and at a stable weight, have realistic expectations, be a non-smoker and your BMI needs to be 30 or less.
l recommend you to make an appointment with a board certified plastic surgeon to talk about your goals and anything you need to know.
Good luck :)

The definitive correction requires the advanced technology of ultrasound assisted VASER liposuction.  I am routinely referred unhappy BBL patients. One of the most common reasons for disgruntled BBL patients is that patients are not able to accurately communicate their desired buttocks goals to their surgeons.  A buttocks assessment tool can be an invaluable tool to communicate to your surgeon the exact buttocks size and shape you are desiring. 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

A secondary BBL will not change the droopiness on the medial lower aspect of your buttocks.  To me Dr. Mendieta  in Miami has described this best. He calls it the "dirty diaper bottom" look.  His proposed treatment for this as a surgical skin excision he refers to as the Miami thong lift. To me adding more volume would make you excessively disproportionate and bottom heavy.  Of course this is a personal decision and perhaps that something you find desirable.  I suggest looking at some of the posted videos by Dr. Mendieta describing this procedure.  Best, Mats Hagstrom MD 

Wow.  You have a really enhanced butt.  More volume might be a bit too much, but it is probably the only way to improve lower pole contours.  How do your clothes fit? If there is still room then go for it!  Be aware that not all the transferred fat will survive, so there is risk of even contours or a less-than-desired result.