So, babies eat more, so they poop more. But I think some snakes really do poop on people when they're stressed.

I think you should handle her more often, actually. They only poop at most once a week, so the days immediately following a big one should be safe. You should also learn to identify The Ominous Butt Bulge of Doom: if you look at their butts, you can usually identify an imminent poop, because it look like the vent is about to pop. That's not a good day to handle. Wait until the bowel movement, THEN handle.

Lastly, when she poops/pees on you, don't put her back. That just teaches her that that's a good way to get out of handling. Wash off, and keep her out for another 1/2 hour or so.

(Poop or urates? Is it white or brown?)