A skinny BBL can be possible in selected patients, but the limiting factor is usually how much usable fat can be safely harvested and how much change you expect. A prior tummy tuck does not automatically rule it out, but it can reduce or change the abdominal donor area because of scar tissue and altered skin/tissue planes. The surgeon would need to examine your abdomen, flanks, back, thighs, skin quality, and scars before saying whether enough fat is available. In the photos, you appear to have a lean frame with relatively limited obvious donor fat, so the realistic goal would likely be a subtle shape improvement rather than a large-volume buttock augmentation, though photos are not a substitute for an exam. If you want a noticeable increase, your surgeon may discuss whether fat grafting alone is enough, whether weight gain is appropriate, or whether other options are safer. The most important points are avoiding over-harvesting and keeping expectations realistic.