1. Is preoccupied with details, rules, lists, order, organization, or schedules to the extent that the major point of the activity is lost.
She constantly writes lists and notoriously plans out everything she's going to do, even if she doesn't do them.
2. Shows perfectionism that interferes with task completion.
With weight loss, either she does well or she doesn't do it at all. One screw up derails her entire day. If she forgets to weigh herself in the morning, she doesn't for the rest of the day. If she eats one unhealthy thing, she will eat whatever. If she messes up a project/challenge, she gives up entirely. There's no rebound.
4. Is over-conscientious, scrupulous, and inflexible about matters of morality, ethics, or values.
But other youtubers do it! She is never flexible in her reasoning. Everything is black and white with her.
5. Is unable to discard worn-out or worthless objects even when they have no sentimental value.
The hoard of random walmart crap.
6. Is reluctant to delegate tasks or to work with others unless they submit to exactly their way of doing things.
This was shown during the infamous Cocoa Puffs freakout. She and Becky were supposed to eat healthy that day together. Becky screwed up, so Amber gave up too. Also evidenced by Becky saying, "We always do what you want to do and go where you want to go." Also evidenced by her manipulating people's advice (O2B, EDDF...) to just be rehashing of what she's believed/been doing all along. She doesn't listen to others, she only listens for what she wants to hear. It's either done her way or no way. Also, again, influenced by her never revisiting the same doctors/therapists after they tell her something alternative to what she believes.
8. Shows rigidity and stubbornness.
Evident by everything.