If you become a nun, do you get to choose your own name?
It really depends on the order, but most of the time, the Superior has the final say in the religious name bestowed. In many orders that I have looked at, the soon-to-be novice gives a list to the Superior that contains three names that they like. Mother Superior prays about it and listens to what the Holy Spirit says. It can be a name that was listed or a name that is better suited for the candidate.
When I applied to the Carmelite Sisters of the Divine Heart of Jesus in Wauwatosa, WI, I was told that each Sister gets to choose her own name for her clothing, but it obviously cannot be the same name as another Sister.
I am currently discerning with the Religious Sisters of Mercy of Alma, MI and I believe that their method is the first one. If I had to submit three names right now, they would be:
Sr. Mary Elizabeth (after St. Elizabeth of the Visitation and St. Elizabeth of Hungary)
Sr. Mary Rose (after St. Rose of Lima)
Sr. Marie Therese (after St. Therese of Lisieux)
I won't be surprised if I get named after St. Therese in religious life. I've been fascinated by her since the beginning of my discernment. :)
I think if I am correct a good majority of the religious orders let you write down either two or three names you would like, but it up to Mother Superior to decide (with much praying) on what name you should be given, if it not on the list that you submitted or is. That is what my godmother (who was discerning with the Dominican Sisters of Mary, Mother of the Eucharist) told me.
Even as seculars of the discalced carmelites, we choose a name. I am in the aspiracny formation and if I am accepted (it takes 6 years to be fully professed)...I will choose
St Mary-Catherine of Egypt.
Mary for Our lady, for st Maria Skobtsova and St Mary of Egypt
Catherine for Blessed Catherine, a servant of the carmelites who died in Compiegne and Servant of God Catherine de Hueck Doherty
Pur Lady, St Mary of Egypt and Servant of God Catherine were connected to Egypt in their life time.