Quran is the book from Allah (SWT) and is an authority.
Quran commands "Do not divide into sects." Period. All those divided into several sects like Sunni, Shia, Dev Bandi, Barailvee, Ahle Hadees, Ahmedi, Wahabi, etc are disobeying Quran and Quran has thrown such people out of Islam fold. They may have the names of Mohammad, Ahmed, Umar, Usman, Ali, etc but Quran has stamped them as hypocrites who have chosen the evil path leading to hellfire.
Just call your self as plain Muslim of Quran.