I think Demeter is an interesting name, although I wouldn't use it myself. Too mythological in my opinion. I just can't picture it on a human.
The goddess Demeter was worshiped in Eleusis which is where Hades kidnapped Persephone (who, at that time was called Kore) - and you can still see the hole he went through. ;)
As I always say: certain names are too ethnic (in this case, mythologic) to be used on a person who has no heritage in that background (.. or used in reality, period). "Demeter" is incredibly closely associated with its mythological ties that I believe it is unusable-- at least in most countries. That unfortunately stands true for most names of relation to lore... Zeus, Aphrodite, Triton, Kronos, Poseidon, and so on and so forth.
If it were to be used, I for one would find it quite unprofessional, pretentious, and a bit childish. Perhaps if you held a Greek surname to pair you may get away with it... otherwise, this best be left to the books. "Demi" could be a childhood nickname.
We have already concluded that "Demeter" resembles "Dementor" (of the Harry Potter world)-- I must add one more, "Demeanor"... which is three letters shy of "Misdemeanor" (a criminal offense defined as less serious than a felony; an instance of misbehavior; a misdeed.)