On the waiting list for an ADHD assessment here. Also, lots of autism in my family (though generally I score low on autism tests).
I have a tendency to do this - I tell stories with many tangents - mostly because I get worried I'll miss out something important/won't be understood. I'll sometimes repeat myself.
I am very painfully aware if time for a conversation finishes and I realise I haven't asked the other person how they are.
I become very aware of my need to interrupt so consciously have to work hard on not doing so - or my ability to pontificate so I hear myself and think "FFS Servalan - shut up!!"
I've had to put strategies in place to make sure I ask a person how they are before they ask how I am, so I can make sure I don't dominate the conversation.
Paradoxically, I'm actually really interested in people and their lives.
If I'm given a "role" of being a listener, then I'm actually a very good, open listener - it's something my job requires (and my job requires me deflecting talking about myself).
I'll generally find that random people talk to me on the bus and they'll go away having told me lots of things about themselves and learned very little about me.
I used to be a Samaritans volunteer too - again, it was something that I was very able to do because the role was about being a neutral person and I was very clear about what my job within that conversation was and the centrality of the person I was talking with. I always focussed totally on them and cared about their stories - open questions, never advising or talking about myself.
So I don't think it's even about being self-absorbed - it's more to do with the mechanics of how to conduct an equal conversation and knowing one's role within it - it can be taught - but it can be very exhausting for a ND person to build up that level of awareness about themselves and to adjust accordingly