Growing up I was always horrendous with what I've learned to be classic ADHD symptoms that were always just explained away as normal.
Some examples would be leaving keys/wallets on busses or misplaced around the house. One time I left all my belongings on a train in my bag when I went back to uni.. Parents said I was careless/didn't value my possessions
I'd watch a film and have no recollection of quotes or scenes that my friends would recall easily - "your brain just doesn't work that way"
Lost interest in classes and didn't do homework or got to the end of a task and couldn't bring myself to finish it (still happens) - "you're lazy/class clown"
looking for things in a cupboard or draw that I could never find, regardless of how long I looked. Mum comes along finds it instantly, accuses me of having a 'man look'
I constantly double book myself then awkwardly have to cancel plans close to the date when I get reminded.
Anyway I've recently been diagnosed with inattentive ADHD. I came across some symptoms and did some research and the more I read the more it fit the bill.
I attended a help group before I sought diagnosis to see other people's experiences as I was worried I was 'making it up' and wasting the doctor's time.
I then took the adult ADHD self screening tool on the ADHD UK website which was the final prompt to see the GP (who funnily enough used the same questionnaire to see if I needed referral). Referral times in Teesside can be years but if you ask to go down the 'right to choose pathway' it was 6 months. This is effectively private providers giving ADHD on behalf of the NHS and paid for by the NHS (another example of quiet privatisation of NHS services, but it's there so why not take advantage) I've been put on the titration list for meds but that's another 7 months...
I think the jist is a lot of these things can be normal or explained away. But if the frequency of these behaviours are often enough to effect you ever day or effect your quality of life then that's when it's probably a condition of sorts.
I've developed coping mechanisms like keeping keys on a retractable cord or writing lists of the tasks that need doing. I keep a diary on excel 'cause the input is quick and easy and additionally my girlfriend has access so she can make plans involving us both so I don't double book (using a diary app has too many steps so despite trying I'd never end up using it).
Hope this encourages you to try and find your solutions, happy to help in anyway I can/offer advice if needed