Name of book needed please

Hi there,

I wondered if anyone can help me find with the title of a book.
I borrowed this book from a library a few years ago and would like to read
it again but I have forgotten the name of it.

It was about a group of people that hunted vampires, one the hunters was a
young girl who couldn't remeber her past and freaked out at having to kill
some vampire children. The vampire children didn't turn into proper vampires
until later in there life and she wanted to try and save them, but it turned
out that later in the book she herself was a saved vampire child and when
she reached a certain age she would revert to being a full vampire.

Would love to read it again but I can't remeber the author ot title.

Hope someone can help.

Thanks,

Anji