Wow, you are describing me. I am exactly the same (total aphantasia, SDAM, ADHD and dyslexia). Every now and again a snapshot, (I like that term, as it's not a fully formed memory), pops into my head, but they are always of negative or embarrassing events from the past, never happy events.
Yes, I've always had problems with eye contact. When I'm talking to someone, after the initial eye contact I feel that I need to look away, but then I become self-concisous of not looking at them and it just makes it worse. I have total aphantasia, a severely deficient autobiographical memory, ADHD and dyslexia. Whether these are a disability, I don’t know as I have managed to be successfully employed for 45 years without anyone knowing about these (although I do think I have been regarded as being unsocial). I do however find them socially isolating because I can’t join in conversations as I can’t remember details of any events, family, movies, books, music, etc, etc.
Yes, I am also dyslexic and for most of my life I thought that this was the only condition that made me different from other people, plus having a poor memory. But now I have found out that I have Aphantasia, plus SDAM (Severely Deficient Autobiographical Memory) and Amusia. I think that all of these conditions are related which is why I have no phonetic ability, I can't distinguish ("hear") sounds and can't reproduce a sound nor sing nor speak foreign languages.
Maybe you also have SDAM (Severely Deficient Autobiographical Memory) if you can't remember past events. I have this as well as aphantasia and I think it is SDAM that is the more debilitating and isolating condition. "SDAM refers to a lifelong inability to vividly recollect or re-experience personal past events from a first-person perspective".
I never really remember my dreams, but just the other day I remember looking at a full colour flight ticket in my dream and then immediately waking up and I couldn't see or bring back the image of it, but what really struck me was that in my dream I actually visualized it as if I was physically holding it!
Interesting to know that aphantasia doesn't always affect memory. I must have drawn the short straw!