As a first time, it went very well. Especially I liked the live streaming to FB and YT.
Maybe you should write a blog post (or a post on the forum) describing what you did for organizing the conference, including technical details. It might be useful for other organizations that are planing to organize such conferences. It may also spark any discussions about improving things, which might be useful for other editions.
For me it was a bit disappointing the low number of followers (watchers), but things in internet happen a bit asynchronously. So, publishing the recorded presentations on YouTube is important, in case someone has missed some presentation that would like to see.
What might be improved? Maybe involving more people and volunteers on the organization of the conference. For example OSCAL has a good tradition of inviting volunteers long time ahead of the conference. How can volunteers help on organizing an online conference? I am not sure. But if nothing else, they may help to spread the word (in social media, etc.)
Allowing people to mark the presentations in the calendar might be useful too. For example using eventbrite or some similar tools. Usually I find it useful for myself when some tool notifies or reminds me before a scheduled event, because I tend to forget and miss them.
Finally, let me share with you this inspirational song: https://www.youtube.com/watch?v=5oEhqht-OgY