In this book there is some interesting information about the socalled Bulgarians* of Macedonia, they call themselves for Macedonians. Thus there is no doubt that those calling themselves for Macedonians are Slavic-speakers.
*Bulgarian was a common term for Christian Slavic speaking peasant in the Ottoman Empire. Reference; Loring M. Danforth 1995, Victor A. Friedman 2000.
From the book “The People of Turkey. Twenty years residence among Bulgarians, Greeks, Albanians, Turks, and …” By Fanny Janet Blunt from 1878, page 11-12.