How many estimated liters of fat do I have for fat grafting to Bbl?

Thank you for your question. It looks like you can achieve good results getting liposuction and BBL, what I recommend you is be consulted by board certified plastic surgeon specialized in Body Contour, who knows individualize each patient to give you the better advice.
Kind regards,Dr. Emmanuel Mallol Cotes.-

My first concern is whether or not you would benefit from a tummy tuck due to the loose skin of your lower abdomen. It appears you do have enough fat for a fat transfer to the buttock. The amount is difficult to estimate without an exam. Once you are examined by an experienced surgeon you may be able to have a better understanding of how much fat you have available.Best wishes,Dr.Bruno

I could liposuction 5 liters and transfer at least 1500 cc per buttock if you wanted that much of a change. I tailor the operation to whatever the patient desires. You do not need to gain weight for the procedure. I perform about 500 Brazilian buttlifts each year, and this
procedure is the most surgeon dependent plastic surgery procedure. Find
a plastic surgeon with ELITE credentials who performs hundreds of
Brazilian buttlifts each year. Then look at the plastic surgeon's
website before and after photo galleries to get a sense of who can
deliver the results. Kenneth Hughes, MD Los Angeles, CA

I do not recommend gaining more weight for this procedure unless you are going to keep the weight on. That being said, you certainly do not need to gain weight, you have plenty of fat for harvesting. The thing that is going to determine how much fat can be transferred for you is the pliability of the skin on the buttocks. Your tissues can only expand so much before no further fat can be inserted. You likely can get 1 liter to 1200cc to each side, but no guarantees can be made by any surgeon, as your tissues will define the endpoint. Good luck!

It looks like from your photos that you have enough fat for harvesting that should be enough for a nice buttock augmentation. An exam in person is essential.