OK. I do have a plot hole now that is bugging me. This one I can't reconcile.
Sussur Bark and Flowers. Completely shuts off magic. You're a sorcerer, and you are seriously effected by this because you've had this wellspring of magic in you your whole life. There is even a cutscene for it making a big deal out of how you can no longer sense magic at all. It's totally messing with you.
So what's the explanation for the Sharran/Netherese Shadow Magic? This I can't explain. If it is a total antimagic force field around you, shutting down all magic, your tadpole should suddenly be free to munch your brain and turn you into a mind flayer. The Netherese Magic would be shut off too which was keeping it in stasis. Therefore, you should feel it suddenly spring to life and start to work on your brain and conscious mind.
But no. Taddy is completely unaffected by antimagic, just like everything else. MAN! That's one powerful tadpole. Even antimagic has no effect on it.
Maybe the flowers only work on the weave as opposed to shadow magic.