If I only have one student attending, do I need to bring other students to serve as voting delegates?

NO. You do not have to bring any students above the number that you wish to bring or that qualified to attend the conference by winning a regional competition.

Also see:

What are voting delegates?

Is my chapter required to have voting delegates?

Do voting delegates count as part of the extra students a chapter can bring?

Can a campaign manager also serve as a voting delegate?