I was delighted to be a part of this event. While you were hoping for bigger numbers, I actually think the size was ideal. So breakout rooms are a terrific idea.
The polls were a great idea to create conversation. I also would suggest doing a facilitated round table. The facilitator can make sure that the quieter or more introverted folks get a chance to contribute. The quietest people in the group often have the most insightful things to say.
Thanks for including me!