Allow me to answer your question as best i can based upon your photos. However, please keep in mind that an in-person, or at least a virtual, consultation with physical exam is first necessary before any legitimate evaluation or final surgical recommendations can be made. No “filler” can fix the flat spots on your lower buttocks. Based purely upon your photos, the main problem appears to be that you had round shaped implants placed and questionably 100% within the gluteus muscles. Other than placing buttock implants within the gluteus maximus and medius muscles (aka 100% “intramuscular”) NOT on top of the muscle, “subfascial” or “dual plane”, the most important factors in creating the perfect derriere and/or hourglass figure with implants is indeed selecting the right size AND shape. I have found the best way to assure this is to simply measure the actual dimensions of the patient’s gluteus muscles (not butt cheek fat pad, which may appear “round”) and quantity and quality/density of these muscles. With these anatomical measurements, I can select an implant that not only significantly augments the buttock but also supplies the correct 3-dimensional enhancement to look as real as possible...with positional changes (eg. bending over and squatting down) and even in the most petite patients that have small/lean muscles and minimal overlying fat. The fact is, nearly 100% of the human population has a more oval shaped gluteus muscles not round. Therefore an oval shaped implant such as the Stanton Anatomic®️ buttock implant conforms best and produces a more realistic contoured outcome, from top to bottom, much better than round implants. Contrary to what many think, a round implant placed correctly within the muscle actually sits up at the top of the butt cheek, creating an unnatural pointy or “gum-drop effect”, not at the lower part of the butt cheek and thus does not contribute to filling or rounding out of any of the lower buttock pole. Height and weight are considered but not nearly as relevant as the above measurements. Final note, because an extremely few number of board certified plastic surgeons specialize in buttock implants, you may have to travel far away from your local area to seek consultation with this particular type of surgeon. Glad to help.