It feels inappropriate to thread-jack but redundant to start a whole new thread.
I'm going through something really similar and am still researching it.
DS is displaying symptoms quite similar to your daughter, except that he's quite outgoing and social. But just like your DD, he's extremely reactive and has a hard time with emotional regulation. His emotional episodes involve screaming, crying, breaking things, physically hurting others, and threatening to run away over something as trivial as losing a game. His doctor ruled out ASD because he has a lot of empathy, just like your DD, and makes great eye contact while speaking.
So bringing things back to your daughter,
my friend, who's child has ASD, advised me to figure out any environmental factors triggering the symptoms and consider the possibility of Sensory Processing Disorder (SPD).
Based on what you're describing, have you considered SPD?
Are there any patterns to your daughter's episodes? Does this happen more at school or at home? Right now, I'm considering a typical school setting that could set off SPD symptoms--fluorescent lighting, loud bells, loud and crowded classrooms with lots of people talking over each other, noisy gymnasiums, bright and busy decorations around the classroom, etc.
We homeschool, but we're not immune to some suspected triggers. DS is extremely athletic. He loves a game of soccer outdoors. But EVERY SINGLE time we meet with other homeschoolers to play sports in a noisy gym, there's an Episode. (And lots of judgment. That's really fun.
Have you considered Occupational Therapy? That's usually the intervention for SPD. We parents are taught to look to conventional therapists for solutions. But just as your experience taught you, that's not necessarily the answer.
So I'm about to give OT a try. Unfortunately, everyone in my area has a waiting list, but hopefully it's worth the wait. Depending on where you live, you may have to commute to a larger city to find a provider.
Also, from what I'm reading, it's possible to have a hard time with emotional regulation and NOT have SPD. But even then, an OT can help.
Finally, I don't think there's necessarily anything abnormal about your daughter "not showing emotion" about her dad leaving. Some kids cope with things in different ways. Some of her lashing out on seemingly unrelated things may actually be tied to that loss.
Good luck with everything!