Awkward...
Well first of all, she might not have checked her email, so give her some time.
Though I won't lie, it's rather strange to just email someone, especially a teacher, out of the blue and act like you see her everyday. People don't usually send personal emails to teachers, especially to ones from 2 years back. No offense, but she might have forgotten who you were, so what's she supposed to say to a stranger?
no offense but it's a tad bit awkward. but a cute kind of awkward. i mean, it's not even that bad. she probably just doesn't know who you are or doesn't know what to say.