Maybe, Sir Knight, she is playing “devil’s advocate,” to make sure that you are sure.
I am a mother of a son whom I would love to go to the priesthood. God has not called him, yet. If, however, my son came to me and told me he wanted to be a priest, I would most likely challenge him on as many aspects of the priestly life as I could think of, not because I wouldn’t want him to be a priest, but I would want to make sure he really wanted to be a priest.
I did this, also, when my husband was discerning converting to Catholicism. I wanted him to be sure he really wanted to be Catholic. I wanted my husband to know what kind of intolerance he would be facing from his anti-Catholic parents and family. He became a Catholic and a very strong one, too. He was able to stand up to his considerable family.
When my younger daughter wanted to follow in my steps and join the Air Force, I did the same. I told her all the things I’d gone through, the discipline and the loneliness that she would face. She went in with her eyes open.
If you truely desire to be a priest; if God has truely called you, you will not shrink away just because your mother, in the goodness of her love for you, challenges you. You will search your soul, just as she wants you to do, and you will face these challenges like the Christian that you are. If she says that you must take classes that you fear, then you must face those fears. You can do this! Your mother wants you to look at the priestly life, which is not for the weak of heart, with open eyes and an informed head, so that you can make yourself ready to go to the seminary.
And like the other poster said, you do not have to be absolutely sure that God is calling you. You may have that doubt for awhile. My uncle entered the seminary, then became aware that it was not the calling for him. He left, married my dear aunt, and fathered my four wonderful cousins. One of his sons, also, went to the seminary, but God revealed to him that his calling was not to the priesthood. He, too, married and fathered three children. His son is now in the seminary and will be ordained next spring.
As I told my son, during his education: it is better to be ready for God’s call, even to going to the seminary–even if you aren’t called to that vocation–than to not be open to the call at all.
I will be praying for you, Sir Knight.