If it helps, I asked my T (after many months) if she gave a diagnosis to my insurance company -- she hemmed and hawed and finally said the same thing as yours (adjustment disorder). She said it's a low level diagnosis and she uses it to keep the bar as low as possible while also meeting insurance criteria.

I was super relieved -- from all that I've read on the interwebs, it's what's most commonly used by T's to get stuff through insurance (and insurance companies know this as well -- so, they know it's not a "real" diagnosis).

ETA: She said the only time it would be changed if someone was on meds, in which case that diagnosis would go in to insurance.