She doesn't lack for confidence, this strapping youngster. Sundberg, 29, has worked steadily up the small-theater ladder and when (not if) she graduates to bigger roles on bigger stages, we'll miss her intimate charisma and ferocity. "Venus in Fur" at the Jungle was a perfect example. "After Miss Julie" with Gremlin showed a vulnerable side, and her beguiling innocence as a young nun in Park Square's "Doubt" made this secondary role stand out.