I think it's a beautiful name and if you prefer to use the whole name, go for it... If insisted upon, people can learn not to be lazy with it. Besides,
Anastasia's such a beautiful name, why shorten it? When I was in gr. 3, I started INSISTING on my full name... and ignored anyone who called me "
Debbie" (eventually started answering to
Deb though)... or later made comments about them having an imaginary friend... In high school choir class, I was next up for something in our class order of things, so I stood up before my name was called, but the choir director said "
Debbie" and I sat down... with the full support and encouragement of a few classmates... It was funnier if you were there.