Do you know her actual age? You got her as a large adult, right? Re-homing older snakes can sometimes affect them worse than with the younger ones- especially if they've only had one home prior. But I doubt that's the issue here- it's possible she's older than you were led to believe?
I'm not a fan of "force-feeding"- if you'd like instructions for tube-feeding, I'll happily pm them to you- it's gentler than "force-feeding" & doesn't make for a weird association or fear of the prey.
By the way, in an earlier post you mentioned trying to feed her large rats- but some snakes prefer smaller ones- have you tried offering SMALL rats? I would.
What about mice? Some BPs have a strong preference for mice- was the prior owner feeding rats, or mice (if you know)??? (& some sellers lie)
I've often found that a snake that hasn't eaten for a long time just doesn't have the energy or feel well enough to have an appetite*, & that once you give them some easily-digested "energy" in the form of a tube-feeding, they feel better & may resume eating normally- sometimes even after only one time. I know many are hesitant to try tube-feeding because of those bad experiences shared by people that did it wrong, but personally, that's what I'd so. There may also be some sort of health issue going on here that you cannot see- might want to consult an experienced vet also.
*It's similar to the difference that an I.V. makes for a human that's hospitalized- without it, they'd just keep going downhill.