Here is a missing person with no photo, no info, nothing. Just the very basics.
She is Tracy Loy Haight. Reported missing from Boise, Idaho in 1994. Could this be FLEK or a previous alias of hers?
She was 31, which means that when FLEK was claiming to be 18, she would actually have been 25, which seems to fit in with most people's suspicions.
She is listed as being about 5"6-5"7 which would make her a little on the short side to be FLEK. However, I really don't think we should be too put off by height differences like this, as it is so easy to guess heights wrongly. Plus, in a case like this one where details are so scant, it seems entirely possible that she didn't really have anyone to miss her and the person reporting may not be particularly close to the missing person.
Edit - Here is the Namus page
https://www.findthemissing.org/en/cases/14083/27