There's a scheduler game called Habitica which is meant to be good if you like playing games.
I haven't yet found an app which is simple enough for me to use but complex enough to have all the things I need on it - I think the biggest problem is that I'd need someone to organise it for me or I use all my time trying to make a schedule and never get stuff done.
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Diagnosed with:
Moderate Hearing Loss in 2002.
Autism Spectrum Disorder in August 2015.
ADHD diagnosed in July 2016
Also "probable" dyspraxia/DCD and dyslexia.
Plus a smattering of mental health problems that have now been mostly resolved.