Who can stand with you, what canon law asks, and what to do if you have no one.
Read →Canon 874 in plain English.
Canons 872–874, 892–893
16 (canon 874 §1, 2°)
Your sponsor is not just someone who stands behind you at the altar. They are meant to walk with you afterward. The Church asks that, as far as possible, everyone being confirmed have one (canon 892), and canon 893 applies the same rules used for baptismal godparents (canon 874). It also calls it desirable to choose your baptismal godparent.
Canon 874 §2: a baptized non-Catholic may serve only as a witness, and only together with a Catholic sponsor.
Some parishes set a higher minimum age (for example 21), ask for a sponsor certificate from the sponsor's parish, or require that a married sponsor be married in the Church. Always check with your confirmation or OCIA coordinator.
This happens a lot, especially for adults coming through OCIA. Tell your director. Many parishes keep volunteers ready to be matched with candidates. Joining a parish group is another good way to meet someone.