She joined the Sisters of Loreto at the age of 18.
Yes, she joined the Sisters of Loreto before she founded the Missionaries of Charity.
Mother Teresa originally joined the Sisters of Loretto in Ireland as a missionary teaching Sister in India. After she received a "call within a call" from God, she became a missionary to the poorest of the poor in India, and later all over the world, founding the Missionaries of Charity to minister to the poor and dying.
Yes, she started the Missionaries of Charity.
She founded the Missionaries of Charity.
Mother Teresa founded the Missionary Sisters of Charity. Actually, the Missionaries of Charity are not just sisters. The group also has priests, brothers and lay volunteers who are both Catholic and non Catholic.
She worked for the Blessed Trinity - Father, Son and Holy Spirit.
Initially, Mother Teresa was sent to India by the Sisters of Loretto to teach in their schools. Once in that country she saw a greater need to help the poor and formed her own order off nuns - the Missionaries of Charity.
When he was in school, he was in a singing pageant and his mother and father liked it so much that he joined the group.
She formed the Missionaries of Charity to do what no other people or groups were doing at the time - minister to the poorest of the poor also known as the untouchables.
A molecule.
A religious group can be called a sect. A religious group can also be called a congregation when all attend the same church. A religious group might have more than one sect, or group of individuals, like the Amish.
The Jesuits were formed during the Catholic Reformation by St. Ignatius of Loyola. Also, St. Teresa of Avila reformed the Carmelites and eventually started the Discalced Carmelite Order.