I've only joined this forum recently but so far been too busy to post . . . until I read yours. I didn't think it was possible that someone else could be in our position.
We also live overseas. Our adult (21) daughter recently diagnosed with AN will graduate US college in May. She was born & raised in Asia, never lived in US until 2016. Until about 2017 she was a classic gym rat, but this devolved over the last year or two into what we now realize was exercise addiction.
Despite this, she was eating well.
In Sept. 2019, however, she began to experience depression and anxiety, and started to restrict food. [BTW we were told by the school counselor at our international school that pre-college graduation anxiety is fairly common among "Third Culture Kids" . . . .! ]
I flew to the US end of October to eyeball the situation, ended up staying a month.
Steep learning curve. The girl was diagnosed with bradycardia but bloods OK. Contacted and followed advice from director of Children's Hospital of Philadelphia eating disorder clinic (who don't take patients over age 18). Long story short: she eats very little and becomes anxious after eating anything w/carbs, fats etc. Plant proteins only. Stable now but still underweight: 1st hurdle is getting her menses back on track. After that, needs to remain stable+eating. For now she gets a physical and weigh-in check 1x weekly by campus clinic doctor; this info is conveyed directly to an FBT-orientated private therapist whom she sees 1-2x weekly (this therapist diagnosed her with OCD and clinical depression); the kid has also begun to see a psychiatrist for medication.
Carrie Arnold's book "Decoding Anorexia" is a layman's compilation of ED research, and has been an enormous help in understanding the chemistry and biological aspects of the illness. Also she accurately describes specific anorexic personality traits that mirror those of our daughter.
Tabitha Farrar's books and blog seem to really resonate with our daughter. It's possible that she will do an online consult with Tabitha soon.
As in your situation, our local ED resources are rather basic. Despite her ordeal, our daughter has been accepted into a US grad school and we're now researching & organizing local resources there, as it's unlikely she'll be able to feed herself adequately without oversight. My husband and I are keeping a very close eye on her. We talk daily to her, and he and I will likely "tag-team" between the US and home in order to oversee her care.
I'm not sure where you are but sounds like we might be in the same or similar time zones. Maybe we can connect/chat.