I would try to "ignore" T in the present other than as a catalyst as she is not part of your "real" life. Think of her as the cue ball in pool/billards, you and your life are the other balls and the game :-)

The remembering of note passing in 5th grade was great. That's just what you are looking for. There may be some bigger, wholistic thing though; I don't like to babysit, be in other people's houses because I was dropped off at other people's houses for them to care for me a lot between the ages of 3 and 6 and moved and changed mothers, etc. so I don't feel "secure" or like I belong and am unconsciously worried I won't get back to my own home and father and brothers, etc.

A related, but inconsequential thing (sort of like your 5th grade note passing) to that is a job I had 25-30 years ago; I had to go through a "lab" that was merely a large room with 4-5 doors in/out and when I was new at the job, crossing the lab to get to my office, I was terrified I'd get "lost" in the middle and go through the wrong door, never to be found again

Work with your memories (that's all they are, like dreams, they're just memories, don't allow them to continue to bother you now you are waking) and ask yourself what you were doing, why you weren't passing notes too and who you wished would write you a note or who you wished to write. Be pleased with yourself that you have such a good imagination and working senses that you could note the notes all being passed around you, etc.

There are lots of memories out there, some more useful than others. Your T's trip is just a memory now, not particularly useful? She may or may not tell you all the places she goes in the future; that's not the issue, if you can find and deal with the original issue, you won't mind how much/little T tells you (or anyone else in your actual, present life).