It is normal to have some nerve sensation changes in the donor area from a fat injection. Wherever the fat is harvested from undergoes a fair amount of trauma, and this can cause the nerves in the area to shut down temporarily. The same thing can be seen in liposuction cases. These nerve changes are almost always temporary, but can take quite awhile to come back to normal - months or even a year. I hope this helps.
It is normal to have reduced or a change in sensation after Lipo for bbl. This usually lasts less than 6 months.
But even a longer recovery if sensation is not unusual.
You had a stomach liposuction to acquire fat to transfer to buttocks. Liposuction areas take 6 to 12 months to regain feeling. The nerves are disturbed and this is normal. If the feeling bothers you ask your doctor about gabapentin (Neurontin). This will help and in small dosages like 300mg 2 or 3 X a day. My Best, Dr C