I have a ball python who is three years old, around 1,600 grams, and hasn't eaten since November!
Try feeding ASFR (African Soft Furred Rats), they are great and will get your snake eating right away. I plan on breeding, selling, and feeding them this June.
It is also around breeding time, so that could possibly be it. After June, if she is still not eating then the breeding issue isn't very likely.
Remember, ball pythons can go months without eating, and usually stay the same weight. Here is a video that might help:
YouTube - SnakeBytesTV-My Snake Won't Eat
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