I don't think it's a lack of priorities. I think it's a judgement and decision making issue caused by your state of mind at the time. You already said you were developing an anxiety attack. When I have attacks it clouds my judgement a great deal. If something is on my mind I have to have it completed before I can move on to the next things, and I won't be able to sleep at all.

This is one thing I think people do not understand about anxiety, bipolar, and depression. It's hard to think when your mind is jumbled up. So you get focused on one thing that makes sense. In this instance, it was cat food for you sick kitty, (even if it was not the cause of your anxiety,) and you would not have been able to think about rescheduling it at all, which is why you didn't. This type of situation happens to me all the time.