The religion of Akhenaten was new. It rejected the old gods of the land but centered around the Aten, the disc of the sun. All other manifestations of the sun were included in the theology, of course, and that is why Heliopolis, the city of the sun in the north, became the second center of the worship of the solar deity next to Akhetaten, the pharaoh Akhenaten's capital. In order to preserve his own divine status in the scheme of things, Akhenaten represented himself as a true "son of the sun" in the guise of Shu, a light-deity who sprang from Ra and formed a kind of "holy trinity" with the sun, including the twin of Shu, Tefnut, goddess of moisture. Nefertiti, the wife of Akhenaten, was the living incarnation of Tefnut and, truly, she was the only goddess of the new belief system, being one with Ra. The unification of Shu and Tefnut with the sun-god preserved the monotheism of Akhenaten.
Here is a page that gives information about Nefertiti being attested in Year 16 of Akhenaten: