Yeah, I'm wondering about that too. When I think about what I understand as "attachment" I would claim that I wasn't attached to anyone when I was a child. I've come to accept though that no attachment doesn't really mean no attachment. There is still something there, the lack of attachment perhaps? Because this "no attachment" thing is not neutral, it is negative, it feels like a hole. Negative of an attachment, like a negative of a photo?

My attachment style as a child could have been classified as avoidant and I am very avoidant even now, even schizoid. But as I said, I consider my experience not as the absence of an attachment, which I imagine would feel neutral but rather somehow turned upside down, into something important that is missing and that leaves a hole.

What do I do with that? I go to therapy, into very intensive one, 4 times per week psychoanalysis. I see its potential to me. Most of the times I don't feel it as a bottomless pit anymore as it used to feel. I also see some hints that I might even learn to enjoy other people's company

ETA:
I've also struggled with the thought that how I'm supposed to build trust and stuff when I don't have anything to build it on. I still couldn't explain it but I guess if there is something hidden inside you, something that has been kept intact, then it might be possible to find it and build on that. Unfortunately, I don't have any guidelines of how to find out if you have something and if you have then how to start using it. I think I found this something for me in my dreams because in my dreams I have perceived the world in a way that is foreign and unknown to me while being awake. Don't really know how to use it though, although I guess I'm already using it somehow without knowing how I'm doing it and how I got there.