Some of the things you mention are part of either dyspraxia, dyslexia, which are both now recognised by those who know what they are talking about to be part of ADHD though not everyon with ADHD experience this.

The most noticable thing you mention is the obsessions. Many would call that OCD and is common with peolple with ADHD though it is all just part of it.
The term attention deficit is deceptive as it is a difficulty regulating attention rather than a lack of it. I can be very attentive, just not to what I want to be.
When a child is seen not paying attention to his work or teacher, they say he have poor attention, but he is being very attentive to the wall displays, and two whisper conversations from other children and the pattern on th carpet and the way the bottom of their shoes feel when they scrape it with their finger nail…………….
I go where my attention goes.
I spend far too long on the PC and NET but can’t make myself stop. I suddenly get a hobby, like bonsai trees, photographing graphitti, keeping stick insects and that is all I do or talk about for up to a year and then I switch to something else.

This is consistant with ASD but when I mentioned all the asd traits my son had to his mental health team, they said, yes they can all be part of ADHD due to difficulty regulating sensory input, emotions and attention(as well as the more comonly known energy levels)
————————————–…
I am trying to make this answer easy to follow as I have trouble reading stuff without my mind wandering sometimes but I have a tendancy to waffle on once I’m typing about something I’m interested in.
This is such a big topic I am trying to be brief.

I will just respond to the traits you have mentioned and put my response in capitals.
————————————–…

Chronic sense of underachievement, feeling you should be much further along in your life than you are
ABSOLUTELY, i KNOW i CAN TEACH AND I EVEN FEEL THAT i COULD DO BETTER THAN THE HEAD TEACHER SOMETIMES BUT i AM A TEACHING ASSITANT AND KEEP FAILING IN FURTHERING MY EDUCATION DUE TO POOR CONCENTRATION, PROCRASTINATION AND POOR ORGANISATION.
i DON’T DRIVE AND LIVE IN A COUNCIL FLAT. tHIS IS NOT WHERE i EXPECTED TO BE AT 34, i KNOW i CAN DO SO MUCH MORE BUT IT IS ALL STUCK IN MY BRAIN.

Chronic problems with self-esteem
tHOUGH i KNOW i AM OF VALUE, i FEEL SMALLER THAT EVERY ONE ELSE, I SAY SORRY FOR SAYING SORRY AND EXPECT EVERYONE TO NOT WANT ME AROUND

Mood swings
I CAN CRY AT THE DROP OF A HAT YET i WOULD NEVER SAY i WAS DEPRESSED, i ALSO STRUGGLE TO BE CALM WITH MY adhd SON WHEN HE IS ‘ON ONE’

Trouble sustaining friendships or intimate relationships, promiscuity
i DO NOT LOOK FOR FRIENDS BUT THERE ARE SOME FRIENDS WHO ‘CALL ME UP AND SAY DO YOU WANT TO HAVE COFFEE’
AND i ENJOY THEIR COMPANY. i HAVE BEEN A SINGLE PARENT FOR A LONG TIME AND CAN’T BE BOTHERED TRYING TO DO SOMETHING ABOUT IT. LIFES HARD ENOUGH WITH OUT UPS AND DOWNS OF RELATIONSHIPS

Trouble with intimacy
HATE EYE CONTACT, FEEL SELF CONSCIOUS SAYING COMPLIMENTARY STUFF, WANT TO RUN AWAY FROM THIS SITUATION

Easily distracted during sex, causing breaks or turn-offs during lovemaking

(Is it normal for the mind to wander during lovemaking? I have found myself thinking about the most random stuff sometimes, things like an episode of a show I recently watched, or some new gadget I recently read about, or something even more random. And it did on occasion cause me to lose focus on what I was doing, which would end up being a turn off)
YUP

Lack of talking in a relationship
YUP iF I HAVE SOMETHING i WANT TO SAY IT GET’S STUCK IN MY HEAD. i **** THAT. i CAN WAFFLE ABOUT MY INTERESTS AND DISCUSS MY ROUTINE BUT NOTHING MUCH BEYOND THAT

Tendency toward addictions (food, alcohol, drugs, work)
fOOD, JUST GIVEN UP SMOKING AGIN, PC, HOBBIES, PUZZLES

Poor writing skills (hard to get information from brain to pen)
WAS DIAGNOSED DYSLEXIC AS A CHILD, THOUGH THANKFULLY, THIS HAS CONTINUED TO IMPROVED AS i GET OLDER (DIDN’T HAVE TROUBLE WITH READING, THAT WAS GOOD UNLESS i HAD TO READ ALOUD AND THEN REMEMBER WHAT i HAD JUST READ AND i LOOSE CONCENTRATION)
i CAN RE WRITE A SENTENCE OVER AND OVER TO TRY AND GET IT RIGHT AND A SIMPLE LETTER CAN TAKE AGES.

Poor handwriting, often prints
mY HANDWRITING IS SHOCKING, THOUGH IT HAS IMPROVED ALSO

Periods of low energy, especially early in the morning and in the afternoon
mY SON ESPECIALLY IS VERY LOW IN THE MORNING AND SLOW TO GET GOING YET HE CAN’T GET TO SLEEP AT NIGHT. i SUSPECT THAT THIS IS A MALE THING AS i AM FINE 20 MINS AFTER WAKING AND LIKE THIS MORNING AM BETTER AT CONCENTRATING ON STUFF (MY HEAD IS ‘LOUD’ ON AN EVENING)

Startles easily yUP

Sensitive to touch, clothes, noise and light sOUNDS BUG ME, i HAVE SUBTITLES ON TV,
mY SON USED TO SCREAM WITH VACUMES AND HAND DRIERS. hE HAS TROUBLE ON A MORNING AS NONE OF HIS CLOTHES FEEL RIGHT

Avoids group activities
i PREFER TO BE ON MY OWN, I CAN’T FOLLOW CONVERSATIONS WITH MULTIPLE PEOPLE AND AFTER BEING WHERE THERE ARE LOTS OF PEOPLE MY HEAD IS BUZZING TRYING TO WORK OUT AND REMEMBER IF i SAID ANYTHING STUPID,
————————————–…
iI think my answere must be too big so I’ll stop.
Feel free to e mail me
also try the site, ADDERS . It is a bit tricky to negotiate as there is so much going on on the screene but there are some great information sheets and articles and the forum is very friendly