I kind of understand what you mean, my memories are very vague, and sometimes I wonder if the parts that are detailed are remembered as a story I’ve told rather than an event that happened which calls their accuracy into question. Sometimes, like you, I’m glad I forget things easily as it makes coping and moving on from negative experiences easier, but at the loss of happy memories I’m not sure if it’s a fair trade.
I’ve started keeping a journal, not of daily events, but anything particular that I want to remember, I put as much detail as I need in, sometimes I write out approximations of whole conversations, or write the whole thing out like a story or fairy tale, and that helps me since I might not remember it myself but I can get a ghost of the emotion from reading about it. I also focus on the emotional aspect of what memories I do hold, so I might not remember what exactly made me so happy last week but I remember that I was that happy.
Kind of tying into that is learning to appreciate the moment. I’m always putting aside a new tea, or saving a meme, or writing down something I want to tell my friends, because having that little token to remind me I’ll see them again soon lets me anticipate seeing them again. I never let myself regret that I won’t remember what’s happening now, because joy may be ephemeral but that’s no reason to look down on it. Everything is temporary to us. I get to admire the trees anew every day because to me they might as well be a different set of trees, I never have to be bored by the scenery from my train since it might be familiar but I don’t get to see it except for in that moment.
In the other direction I know difficult moments will soon be distant memory, no one can yell forever, disasters must relax after a while, things return to normal, these moments only enhance the excitement of seeing friends, or the beauty of the sun setting as I make my way home. I keep a seperate log of things I need to remember, health problems or customers who might be trouble later, I don’t read that unless I have to. Sometimes it’s difficult, there’s a lot of things I wish I remembered from my childhood, or even just last year, but once you train yourself out of looking for long-term detailed memories and focus on enjoying the moment it’s a lot easier.
That said, it could also de a symptom of depression, which some people certainly feel upon delving into their aphantasia. Either way I hope this has helped a little bit and given you a few ideas? Accepting the fleeting nature of all emotion and experience is difficult but I found it rewarding.