I was thinking that sounded a bit small, theoretically females can get up to breeding weight after their 2nd or 3rd winter. Her weight would need to quadruple in the for her to be up to breeding size for next year.

But I'm not all that experienced, just a bit of reasoning on what I've read about ball python growth rates, so don't take my thought too seriously! Also, even if she is small for her age, that doesn't meen she is undernourished. I'm sure some snakes grow slow compared to others, just as some have a smaller adult size than others.