Sorry, but this kind of drug speculation seems so out of place.
It seems like it comes up every day, it comes out of the blue like spaghetti thrown at the wall, and it doesn't fit anything else.
It's almost equivalent to: maybe she works for the MI6 and was on a secret mission in collaboration with the CIA, and they are flushing out a terror cell (which would also explain why she was rushing around and nobody has heard from her for a week, and why LE is putting out inaccurate info.)
I could see how it could maybe fit some other person's experience or situation, but no relationship at all with HEG.
There is no evidence or hint of evidence that she had any history or interest with this or any drug, other than a mucolytic she was taking when she was sick.
You can read the tweets of her account and her roommates' accounts to build a bigger picture of her daily life at school and out of school. She is a good student with tight friendships and strong and open family. The re-tweets give a sense of what is important to her and what she identifies with (examples are overthinking and tallness, and occasionally, hot guys). She seems pretty open about things and pretty normal.
Adderall or addiction and secret drug buy don't fit. They are in a completely different reality.
She was looking for something:
A person
A car
Drinks for the party
Something she lost
-ID
-Phone (though LE says texts happened)
Is she backtracking from earlier during the day?
In all the videos she is looking, or else she is walking directionally and quickly. Until she stops. With JM?