I don't have an answer about your shirt. Maybe it was her dryer sheet or detergent, or lotion she was wearing that rubbed off on you? I usually miss my T more after seeing her but you say that's unusual for you.
It could have to do with what you brought up about not asking her about herself lately. Did she reassure you that it was okay to ask? Do you feel unsettled or unfinished about your discussion of it with her?
I'm sorry you're missing her so much, and hope that you can figure it out, or be able to cope. I know how strong those feelings can be!

