I have been going to Mass at Catholic churches off and on throughout my life, and have considered myself Catholic. However, my mother chose not to have me baptized as a child because she wanted me to be free to choose my own path. I am now an adult. Will I need to go through the same process someone who is converting from another religion in order to be baptized and receive my First Communion?
It depends on how educated you are in the Catholic faith and on the process your parish uses to initiate non-Catholics. If you are unbaptized, it is indeed likely that you will be asked to enter the RCIA program. RCIA stands for Rite of Christian Initiation for Adults and is intended to prepare non-Christian adults for baptism, First Communion, and confirmation. If you are unbaptized but believe in what the Church teaches, you would be non-Christian (since baptism is required to become Christian) but a believer in Catholicism. Once you are baptized in the Church, you will be a Catholic.