Can my lower butt ever get fixed?

Buttock “sagging” is usually a combination of loss of volume or deflation (after weight loss or post-BBL) and/or the effect of aging, genetics and/or gravity. So, I personally first treat patients like you by restoring volume to the buttock with a buttock implant. This will create a more desirable smooth and rounded perky buttock profile. If not adding volume with an implant, the buttock will be shortened but may appear more flat with just a buttock lift. A lower buttock tuck is usually then performed at six months following implants. In this sequence, the implants have fully settled into final position so that any remaining loose skin can be most accurately identified and removed with the lower buttock tuck. Please note, because an extremely few number of board certified plastic surgeons specialize in buttock implants, you may have to travel away from your local area to seek consultation with this particular type of surgeon. Glad to help.

The correct procedure for your condition is a tuck which involves excitising skin.
The procedure is best described by Dr. mendieta in a YouTube video called the Miami Thong LIft.
I suggest you watch that YouTube video and then try to find a local plastic surgeon who has experience doing the procedure. Finding someone who has done the procedure enough to deliver a consistent quality results may be a challenge. You simply need to call around and consult surgeons until you find one.
This cannot be corrected with Liposuction, fat transfer or any other procedure except cutting out skin and repositioning the lower gluteal fold.
Best,
Mats Hagstrom MD