Thanks for all the comments on how to help with tantrums and eating.
Yesterday, Isabella ate much better, but still was a holy terror when told NO or given commands. I've been trying to explain to her why I tell her NO or why I tell her to do or not to do something. I feel it gives her a reason, though, I'm not sure she quite understands the reasoning yet (but it's a good habit for me to get into because the WHY phase is on its way.).
Timeouts seem to help and see understands what timeout is, often coming to me after timeout with a hug and a SORRY. Now if we can get to a place where we know timeout is the next step and she stops her behavior before timeout (but that's wishful thinking at this stage.).