Today, after a group class, I asked one of the instructors I've sparred with several times what I need to work on the most.
"Relax," he said. I'm getting better, he told me, but I'm still too nervous/anxious in sparring.
Technically, he also said I sometimes over commit--my shoulder may be actually farther out than my foot on a punch. Then it takes a moment for me to recover--and in that time, my opponent can move away, counter strike, etc.
But mostly, he said, relax. "We're not going to break you in half," he said.