It sounds like you are headed on the right track but thiscould derail and I want to clear some things up...
1. Your boa was doing fine until the move to a largertub...that was the first problem...loss of security. Hungry critters of goodhealth will eat if they feel secure.
The second problem, and you can kill a young insecure boa bydoing it, was forcing the issue. Never chase or tap the snake with itsfood...there is a reason the boa is not eating, causing fear and stress is notthe way to fix the issue. Do not put a fearful boa in a separate enclosure tofeed.
This boa is a little insecure, treat her as such (less or nohandling, don't mess with her a few days before feeding and definitely notuntil a meal is digested) -she will come around if you're patient. There is oneplace a young boa should feel secure (in her tub)...make that happen.
To keep this boa on the right track: Stick withthe proper prey size and move feedings out to two weeks (you want her to behungry with a strong feeding response). The only 'game' I would play with heris put the food near a vent on the outside of the enclosure. Come back in anhour or so and give it a go. I used to breed rats in the basement. I could goin the basement for just a minute, not touch anything, then go into the snakeroom and the boas would try to eat me without ever opening an enclosure door.Their sense of smell is incredible...use it