Yeah, Volume 2 isn't really a story worth telling anymore, They were only about to really begin when it ended. the story arc was going to be about the virus outbreak.
You could cull certain things to add elsewhere, just mind continuity on certain things like Peter's hair.
Volume 3 while entertaining was still a bit sloppy in the story telling. It probably would be best to choose a particular plot thread and cut awa ywhatever doesn't relate.