HI Trisha,
It seems everyone gets nervous teaching in front of peers, and not so nervous when teaching students. I know I do! The rationale for your lesson was to have students communicate without embarrassment and to develop communicative competence by themselves. So yes, I agree that you should have had a few practice drills first with the students. Also I would split the class into groups of maybe 5 or 6/group, just that way students didn't have to yell to each other across the room. Also in small groups, children (and adults) usually feel more at ease to talk, and aren't so nervous.
Overall, your lesson accomplished your rationale which was to allow students to communicate freely and without embarrassment. Well don!!