Thanks for your responses everyone. I'm glad I didn't send her the email after all. I had a new email box pulled up in my Gmail account and was starting to write something...until I couldn't think of anything to say besides "thank you for meeting with me yesterday." Anything beyond that, to me, would have come off as strange and there really wasn't a need to write a whole email just to say that one thing.

So instead, I created a new Word document and wrote her a letter highlighting my gratitude and describing some of the feelings I've had lately. I wrote it from my current perspective to be able to read at the end of the therapy process to see how far I'll (hopefully) have come by then. I also wrote it to give to her at the end to thank her for all her help. I think this will be more appropriate than an awkward email after Session #1, when I'm pretty much still a stranger to her.