About the cultural biases thing, many have rightly pointed out how Jesus was the last person to let such things cloud His judgement (as if that were even possible). Tax collectors, prostitutes, lepers etc. These were roughly equivalent to inviting serial killers over for dinner today. So if He wished to call one of His female friends to be an Apostle, He would have, no reservations. But He didn’t.
Not even His mother. Think about that.
Reading the story of the Samaritan woman at the well will also reveal that he viewed women as equals. No man of that time espousing its particular gender roles would have spoken to her as he did: as an equal, yet not as a synonym for a man. (This last distinction regarding complementarity is an important and underappreciated difference)
But as to the pastoral issue of bearing witness to your mother, it may be fruitful to do more than just say what you are reading here. One of the major enablers of this particular heresy is the widespread distorted notion of the priesthood as some kind of promotion, status symbol or reward. It is none of those things, indeed is a calling to service. This is not to say it cannot be rewarding, but that is different. You will not likely meet with much success unless you address that misnomer.
Good luck and God Bless