I'm in a similar situation, just with an older snake. I got a banana female that's about 300g now (was 335 two weeks ago), breeder said she was pounding f/t weaned rats (he has lots of positive feedback online including faunaclassifieds) and she's been refusing everything I've offered. I fed all my snakes a few days after I got her, so I figured I'd try feeding her and wouldn't be surprised if she rejected it. Then the next feeding was about 5 days later and she refused again, then I tried a live rat but it was a bit big, she seemed more interested but still not eating. Then last night I tried again (f/t weaned) and she didn't take it.
I've been using paper towels for substrate (breeder used shredded aspen) and have them in 15qt tubs (breeder had v18s) so I'm thinking I need to give her a hide for her to feel more secure (or just cover the front of the rack) and maybe put some shredded aspen in there to make it more familiar. I also have a reptile store in my area that I can buy asf from pretty cheap, so I think I'll do all that and try again Friday to feed. Think I'm missing something?