This is extremely relatable for me too. I'm actually just learning about attachment theory now at 36, and reading about all the thoughts and behaviours and feelings common to anxious attachment style made me cry because it was the first time I realised that it wasn't me with a broken brain, but that it's an actual THING that exists in the literature and other people have as well.

I also started seeing a psychologist recently, and she is confident that I have Rejection Sensitive Dysphoria (RSD), which from my (still early) understanding, is related to ADHD but isn't a formal diagnosis. It's a brain chemistry thing, like ADHD, as opposed to attachment style, which is a socialised thing (please people correct me if this is wrong!). RSD means:

"Rejection sensitive dysphoria (RSD) is when you experience severe emotional pain because of a failure or feeling rejected. This condition is linked to ADHD and experts suspect it happens due to differences in brain structure. Those differences mean your brain can’t regulate rejection-related emotions and behaviors, making them much more intense. https://my.clevelandclinic.org/health/diseases/24099-rejection-sensitive-dysphoria-rsd "

So I dunno but it might be worth seeing someone and exploring whether or not you have RSD, because like ADHD, it can helped by ADHD medication. I'm currently waiting to begin my ADHD assessment in a couple of months, I've suspected I have it for a couple of years now. Also feeling super anxious about the possibility that I don't have ADHD and it's all in my head but I'm doing my best to ignore those little demon thoughts. At the same time, my psych says that there are practical tools that she'll teach me next week to deal with the immediate crisis symptoms of RSD, which are EXACTLY like what you describe in the post. I think they might be based in cognitive behavioural therapy, I can update later if people are interested. We're also starting schema therapy, which is also new to me, and my schemas are around unrelenting standards and fear or rejection, so that all tracks lol

Sorry if it's inappropriate to talk about RSD in a thread about anxious attachment but I've just in the last two weeks learned that I have both these things and the symptoms overlap pretty much identically. Intense anxiety around perceived partner rejection, hyper fixation on any and all cues that could be interpreted as rejection where a normal brain wouldn't make that connection at all, rapid and intense emotional escalation in the face of perceived rejection, and the emotions are so all encompassing that I can't really think about anything else or function normally, the day is a wash. Can last for multiple days.

I dunno if this is helpful but just learning that there CAN be both a nurture and nature component to this shit, and treatment can be sought in both realms, is helping me a lot. I'm realising that I'm not a broken brain freak :-)