As much as BPs are recommended as beginner snakes, they definitely aren't what I'd call "easy". That award has gotta go to something like a corn snake, in my opinion.
But to your problem, I would definitely space out feeding to about as often as she has historically eaten for you as a start and keep an eye on her weight. Maybe just offer once monthly as long as her weight stays steady.
Also, I'm not sure where you buy rats that a BP would have to have $5 rats (unless you feed live?). She may choose to eat more regularly if you offer a size smaller (smalls if you offer medium, or medium if you are offering larges). If you do use frozen, it is definitely cheaper to order online. My small rats cost around $1.50-1.75 & mediums around $2 each.
If you feed F/T, I highly recommend getting a cheap hair dryer and using that to thoroughly heat the head of the rat before offering. You may see better response from her this way than warming under a lamp or by dipping in hot water.
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