Is it normal to forget entire days if my routine changes?

Yes, this can absolutely happen with ADHD and it is related to how memory and attention work together. Many people with ADHD rely on routine as an external scaffold for memory. When the routine breaks, the brain has fewer anchors to encode events, so the day can feel blurry or missing afterward. This is not dissociation or a memory disorder. It is often a result of attention being spread thin across new decisions and transitions. When the brain is busy adapting, it records fewer details. Using light structure, even on off days, can help anchor memory without needing a rigid schedule.