What options besides fat transfer and filler can replace volume after excess fat removed during a lower blepharoplasty?

It is impossible to give you good advise without a series of appropriate photos. Very likely, fine fat grafting with micro and nano fat grafts would be one of the options. In person consultation with a board certified plastic surgeon with known expertise in fat grafting, is recommended. Good luck.

The two things you mentioned- fillers and fat grafting- are the most common treatments to improve hollowness under the eyes. If you are unsure about results you may want to try fillers first since they are reversible with hyaluronidase if you are unhappy.

I am very sorry to hear about your result. In my opinion, nano and micro fat grafting are the best methods for correcting the deformity you describe.