It may be time to give up WordPress.com. There is little day to day difference in managing a self-hosted version, but there is a world of opportunities that will open with a few well selected plugins. You mentioned you’re volunteering for an organization. If the issue is paying for hosting, Dreamhost and HostGator offer free lifetime hosting for US based 501(c)3 non-profits. Dreamhost’s process is the easier of the two. (Disclosure, I’m an affilate for both…but look ma, no links).
Between free hosting and plugins, your organization’s events should get all the attention they need.