Yes fair enough! Obviously please know I am not a psychologist, or any sort of professional - just a woman in her forties who flew under the radar but definitely would have been dx'd as a child in this day and age. A variety of aspects struck me from the OP's posts but the main one was depression in her DD's early teens and struggles in secondary which is often classic in autistic girls, especially ones who are bright/academic. Because of that academic capability, often our emotional struggles are written off or minimised - and this I think can REALLY flare up later in life due to delayed processing. Ever go through a situation and think, later, "well, THAT was unfair!" Yeah, this happens a lot with us, and I'd say it's very likely it's happening with OP's DD. Except OP's DD seems to be hyperfocusing (another autism trait) on her childhood and the specific unfairnesses like extra internet time/different holidays. This strikes me as her DD trying to "logic" her way out of an emotional situation (which again tends to be an autism-specific thing).
If, emotionally, someone is wrecked, sometimes one looks to the outside to explain why. Call it wrongly directed blame, call it desperation, call it misdirected focus, it's hard to say. University years can be BLOODY hard for autistic folk, we're fed the idea of "here's where you get lifelong friends!" but in reality our executive function is getting HAMMERED by things we never had to do before (food shopping, bills, planning, classes/lectures, so where's our ideal university experience?? Nowhere! Why? Is it my fault? Whose fault is it? How can we solve it? Oh god. Is it the way I was brought up? Am I screwed up for life? What CAUSED this?). So now you're looking at childhood causes because holy fuck, is adulting hard. How is everyone else cruising through? Making friends and going out for drinks effortlessly? Especially, ESPECIALLY, if one was a "gifted" child, because many academic things came so easily to us, why can't THIS - being an adult? Forging relationships? And then one turns inward... this is honestly why I say it's so important to look at brain wiring because if you are ND trying to be NT in a NT-focused world, it is so bloody hard.
And then the final reason I thought of autism was that OP's DD's dad is an engineer who doesn't tend to make small talk and isn't a people person. That... is my dad all through (minus the engineer aspect. He was a mechanic). The conversations we have? They're all fact-based. Very little emotion. I love him so much! But if I ever went to him with relationship issues, or feelings, he would be a deer in the headlights! But lots and lots of autism is genetic and engineering is a classic autistic male occupation (my son is autistic and aiming for mechanical engineering) and so that to me was another flag.
Listen, take this with a grain of salt. Take it with two, or three. I have nothing but sympathy for both OP and her DD. I think they are both trying. Trying HARD. I think OP's DD will find her niche in life and spread her wings and begin to fly, and somewhere down the line they will be able to sit in a cafe together and speak of shared interests. I think the OP should not rule out autism....nor ADHD. (I have one child with each, but they can easily be co-occurring conditions). I think the OP should practice radical self-care as much as possible, and realize that blame is easy to throw around when one is struggling to make sense of one's identity. I am off now to have a glass of wine and I may not check back for some time - it's been a rough day parenting my ADHD girl and I'll likely be easily bruised if I come back to hard words (this is not my way of shutting anyone up or preventing posts, just me saying I might not respond), but thank you for asking that question, @ToucherGouterPlus and OP, I'm wishing you all the very best.