If you are not Catholic you may not receive the Eucharist, that is, the Body and Blood of Our Lord and Savior Jesus Christ, because the sacraments Christ gave to His Church are reserved for members of his Church. To receive worthily one must be baptized and receive enough instruction to understand that this is not just a ceremony but the actual Presence of Jesus Christ in the Mass and the Sacrament, and be admitted into full Communion with the Catholic Church through Confirmation and a profession of faith. The people in charge of religious education for teens and young adults in the Catholic parish closest to you, or where our cousins belong, can tell you how to proceed if this is something you wish to explore.
Welcome home.
If you were baptized Catholic, but never received religious instruction or were prepared for the other sacraments, you nearest Catholic parish has a program for people in your age group to do that.
You really have not given us enough information to answer in a way that meets our specific needs, but the Catholic priest in a parish close to you can do that. You might ask your grandmother for help in doing this if your parents are not inclined to help you at this time.