I would not be concerned with size of prey with yours, hardly anyone here can claim the have a 26 year old BP you are obviously doing something right. BPs size can also be genetic, a breeder friend of mine has a 6500g wild caught female he got from outback years ago that came in at about 5900g. My clowns are in the 3500g range and they get fed the same size prey as my other females of the same age but have grown much larger. I feel soon I will need to step them up from mediums to large rats because they are looking for food like a retic.