Due to censorship, Nel's clothes, in her adult form, were altered slightly between the manga and the anime. The manga clearly shows the lower.
As the smoke clears, Ichigo, Nnoitra, Orihime, and Tesra see Nel in her adult form . Nel uses Sonído to take Ichigo to a safe distance, evading an attack from.
She is also known as Nel Tu, and she is a small, good-natured, childlike Arrancar . Upon regaining her adult form thanks to Urahara's bracelet device, Nelliel.
245 "The Way Without Enemies". and her adult form is later revealed in BLEACH Volume 33 CH. Neliel's full name is more commonly shortened to "Nel Tu".
So i was rereading Bleach, and I saw that Nel was still a girl when Ichigo fought Opie, and then in her next appearance, she regained her adult.