It's not always easy to covert a BP to taking f/t prey, but it's really worth the effort for your pet's long-term health & freedom from injuries, and for the expensive
vet bills you avoid. Snakes don't always respond that well to antibiotics, & medications are not risk-free either. I'm glad you're thinking about trying again to convert.
And as CALM Pythons said, you really should avoid feeding the larger (adult) rats no matter what.