I'm from Nigeria (West-Africa).. And while I agree that west african countries cannot be classified as southern africa, i also think "sub-saharan africa" is too broad.
I agree that "Sub-Saharan" is very broad, but I guess OP intended "Southern Africa" to be "Sub-Saharan" Africa. Unless the equator was intended to be the dividing line- which would make the definition of "Northern Africa" somewhat unconventional as well.