Working Memory Issues
My short term memory is fine (e.g. if you told me to remember five random words and repeat them back at the end of our conversation. My long term memory is okay (and actually very good on topics of interest) but my working memory is like Dory from Finding Nemo.
I can't remember birthdays, appointments, to pay bills; reply to text messages, tasks like giving the cat a worming tablet.
And 'normal' people tricks to remember don't work - I can set reminders on my phone but if the reminder goes off at a time I can't 'do the thing' then I'll forget again within 30 seconds. If I write a 'to do list' then I forget that I have a list.
Something like this can be of critical importance to me and I absolutely desperately want to do it but that makes zero difference to my ability to remember to do it.
I might go several weeks where I remember I need to do something really important every single day but forget again by the time I'm in a position to do anything about it.
Losing Things
I think this is linked to above. As soon as I put things down I forget where they are. Obvs this happens to NT people but I don't think it happens several (hundred) times a day.
Hyperfocus
When I'm really interested in things I'll go down a rabbit hole and can hyperfocus on them and get through an incredible amount of research / work.
Racing Thoughts / Impatience / Interrupting People
I have periods where my brain feels like it's working on hyper-speed. When this happens I can join dots and see patterns in things at work very easily and come up with lots of ideas but it keeps me awake at night with racing thoughts about all kinds of topics (not stress...new ideas, making connections I haven't made before, etc).
My energy levels and motivation are very high at these times (hello high dopamine levels!) but I can get impatient and frustrated that NT colleagues can't keep up.
It also means I interrupt as the pace of meetings seems unbearably slow and I feel like I'm already two steps ahead (sounds arrogant but I literally can't help this!).
Shutdowns
On the opposite end of the scale I have periods (usually days, occasionally weeks) where I feel like a robot who has been powered down. I have no motivation, the smallest task feels totally overwhelming. I can't even get out of bed or brush my teeth. This is severe low dopamine levels.
I often have Parkinson's style tremors at these times which are also a sign of low dopamine.
Spatial Awareness
My spatial awareness can be pretty bad. Before I drove I constantly had scabby knees from falling over. Now I drive my car is seriously beaten up partly from spatial awareness and partly from not being observant/a bit distractable.I walk into things a lot.
Addictive Behaviour
I've been through periods of being a workaholic, having issues with shopping, I get easily addicted to silly games on my iPhone to the point I'll stay up until 2am playing them even though I don't want to (and then have to delete them), addicted to phone / social media. Nothing bad enough to need any kind of treatment but all beyond the average NT person.
Binge Eating
Linked to above, binge eating disorder is a common symptom as our brains subconsciously realise we have dopamine problems and seek it out via sugars and carbs. The binge eating feels compulsive like you don't have any / much conscious control over it.
Caffeine
I drink shit loads of coffee, to the point that I'm well known for it among colleagues as while it's not outside the experience of NT people it's unusually high compared to an average person.
I don't feel any stimulant effects from it - I never understood when people said too much caffeine gave them the jitters / anxiety / hyper feelings. I feel calmer and more focused and can happily drink a large Starbucks with 3 espresso shots in it and then go to sleep.
Again, this is your brain self-medicating. Caffeine has a mild stimulant effect and stimulants have the opposite impact on ADHD'ers than NTs (the ADHD meds I take are basically amphetamines/speed).
Reading
Slightly weird one but I have two approaches to reading books - if I find it super interesting I'll read the whole thing in one or two nights. Otherwise I read about 20-30 books at any one time - so I'll read a few chapters of one, then switch to another, then switch again, then maybe start another, then switch again. I do finish them but cycle between a large number of books on different topics.
Problems with Transitions
I love big life transitions (new job, new house, etc) and don't find them stressful (probably because of the dopamine boost) but small daily transitions are challenging.
So transitioning from 'being in bed' to 'getting ready to go to work' can feel impossible.
Transitioning from 'working mode' to 'not working' can be hard, I find it hard to stop working.
The worst is transitioning from 'evening time on the sofa' to 'bed' - I can be really, really tired and desperately want to go to bed but be almost stuck in a kind of mental paralysis until 4am or 5am at its worst.
Lack of Routine
I really struggle with establishing and following routines. For example, I don't have a routine in the morning that I sub-consciously just follow out of habit which I believe is how NTs tend to work.
This means I forget things NTs find it hard to understand how they could be forgotten like brushing teeth or in any way planning what I might eat for dinner (it's almost like a surprise every day at 6pm when my DH asks what I'm having for dinner and I always have no idea and haven't thought about it).
Impact on my Life
For all of these things it's the level of impact on my life that makes the difference I think.
NTs might do all of these things occasionally but for me they are constant, many times a day and have a huge impact.
Not just being a bit annoying but massive impacts like forgetting to clean my teeth so often that I am in danger of having serious gum disease, binge eating to the point of being morbidly obese, forgetting bills to the point of defaulting on a loan even though I have the money to pay and want to pay(!), losing many friendships because I forget to respond to them for months and months(!)...