What's that chord?
You're playing C-G-B.
C-G would be a C5 chord, and adding B would make it a C5maj7 chord, if such a thing exists.
I don't think you can invert C-G-B to any kind of G chord that makes sense. Adding C to a G major chord would make it a G11th chord, but it would be more common to keep the D and replace the B with a C (G-D-F-C), which is actually G7sus4.
I think your best bet is to know your chords from music theory. It's less than an hour of reading material, so it's not that complicated.