Hi I Had a Bbl 12 Weeks Ago I Have a Soft Lump on my Left Butt Cheek is This Fat Necrosis? (photo)

I would wait a little longer and some of the fat uneveness will even out.  The hard lump is probably a larger area of fat graft as fat necrosis takes time to become evident.  Small little tweaks are not uncommon with liposuction so I would not hesitate to discuss this with your surgeon.  Best wishes!!

   The lump may be fat necrosis, but this will usually resolve.  However, I must say that as common as one would think this would be after Brazilian buttlift, I do not see it very often.  With regard to the other issues, I think you have a nice result.  However, I cannot fully evaluate without preoperative pictures.