Is my butt fixable? Fat transferred too low or only to bottom. Flat top

Dear girl12345678,
it is hard to tell for sure without an examination. Based on your photos, it looks like you would benefit from BBL revision surgery and liposuction. If you are considering a surgery, I would suggest you to consult a board-certified plastic surgeon. Only after a thorough examination you will get more information and recommendations.
Daniel Barrett, MD
Certified, American Board of Plastic Surgery
Member, American Society of Plastic Surgery
Member, American Society of Aesthetic Plastic Surgery

You are in good company with many others who had high hopes for BBL but instead received disappointing results (lumpiness, unevenness, lack of projection in the central buttock, etc.). It is not quite as much the quality of the doctor but rather the quality of the procedure that is a large part of the problem. Thus, going back for round 2 BBL most often produces the same disappointing results but at another financial loss. Buttock implants indeed provide a more reliable, predictable, relatively safe, and permanent result, especially for adding projection to the buttock and often smoothing out lumpiness. Please keep in mind that an extremely few number of board-certified plastic surgeons specialize in buttock implants so be sure to consult with one that is reputable and experienced. Unfortunately you may have to travel long and far away from home to find this particular surgeon. Glad to help.

It appears from your photos that you could get a better shape with another fat transfer. Take your time to pick the right doctor, so your expectations are realistic and you get the best result you can get with this starting point.