I often feel exactly the same way. I have all of my outings planned far in advance, and I always, for example, go grocery shopping at the same time in the same way every week. This helps manage my anxiety somewhat, but in the case of outings where I know unpredictable social interaction will be happening - at my job, for instance - the feeling of dread borders on a 'fight or flight response' level of anxiety. Like you, I often 'waste' my Sundays worrying about my Mondays, and my Saturdays worrying about my Sundays, and so on. It's been this way since I was a child.