I was reading Lost Tales 2 today, and in the original version Tolkien explains this.
It says, and this IS accurate if not word for word, after she cut her hair "nigh to her head" (and it even mentions her having difficulty doing it and being unhappy about it) her hair "grew as it did before" she used magic on it. So techically her hair should be shorter than most depictions--how long was she in the wild before they went back to recover the Simaril? Not long enough to regain her long hair, unless an Elf's hair grows faster than human hair.
Sorry *dork rant over*
Very very lovely piece. I especially love Sauron. Instant fave