What might this behavior be a sign of?

I need help figuring it out, sorry for the long post. The girl I’m talking about has turned 18 recently, just for some background.

Since she was very young (like even since she was 3 years old), she used to get sick a lot with no apparent reason (a lot of tests were done and nothing was found). Sick meaning feverish, with very intense headaches and weakness, so much so she needed medical help.

Afterwards, when she was only about 5 or 6, she didn’t want to shower with her sister anymore and wanted to shower entirely alone (saying to her parents she knows how to do it already), and also wanted to dress herself. Idk if it has anything to do with it but she was also afraid of her mom’s naked body (specifically breasts) and it was laughed off by her family.

She was suffering from daily nightmares every day for years, and always wanted to go to her parents’ bedroom to sleep with them since she said she couldn’t sleep alone. She said the nightmares were like “TV channels” and that they would “change” but also the same few one were on repeat. There was a specific one with a red monster.

She generally doesn’t remember much of her childhood. After the age of 6 she would start to eat a lot of food (even if there was never a food shortage at her house), and hide that she was eating, throwing cups and plates under tables and closets.

She would not talk a lot to her parents and sister about personal things (neither about her feelings), and at elementary school she again started being sick a lot, although later it was discovered some of those times were her making herself sick (one time she had shampoo in her eye and kept putting it to make it red and injured).

Despite that, she would do excellent at school. Very high grades in every class, she took extra classes (advanced physics and biotechnology) and advanced classes in math and English.

Outside of her house, she’d be very quiet, polite, calm, even cold. But with her family she’d sometimes burst out (never physically or violently), and could go days without speaking to anyone out of anger and frustration. Her family used to say to her she’d “victimize” herself (saying she always tried to make herself the victim in arguments) and it has bothered her deeply.

A few times (approx at the ages 10, 14 & 16) her mother tried to take her to therapy for her eating habits and behavior, but after a few sessions the girl would not want to go again, saying she was okay.

She is (generally) attracted to men, but she almost never talked about it and was always more careful around men too.

At 17, she suddenly suffered from seizures and it has been revealed that she overdosed on 100 pills 2 days beforehand without telling anyone, and they found out only after blood tests (she didn’t even confess). They also found burn, hit and cut marks (fresh and healed) on her arms, no one saw it since she was always with long clothes. She apparently also ate and threw up after every meal.

She was sent to a psychiatric ward and stayed there for 3 months until being released, and treated with depression meds. After that, she was said to experience a manic episode (with psychotic features) and so was diagnosed as bipolar.