Hi and thank you so much for your responses!
Yes, I had considered that she might have been an angel and it seems the most likely explanation. I wasn't sure, though, as I'm not religious so I didn't really think an angel would be interested in me! I had, therefore, thought it might have been some other entity that was able to interact with people, but I couldn't imagine what that could be, or why...I think angel sounds the most plausible thing but just wanted to put my story out there to see what others thought.
Thanks again for the replies and it's nice to meet you!