I don't think they did much between May and July because Brian was recuperating. They only gave him two months before they went back on tour in July.
I would love to read both Brian's perspective on the day of his surgery and Nick's perspective as he and the guys performed for Disney World's Grad Night without Brian. Was that weird for him? Did he feel guilty? Worried?
I would also love to read the first time Brian and Nick talked after his surgery, as well as the first time they saw each other afterward. I'm not sure when the latter was. I don't think any of the guys went up to Rochester to visit Brian in the hospital in real life; I've never heard them talk about it if they did. So did they not see him again until just before the tour resumed? I'm not sure.
I think once you get past the surgery stuff, a two month time jump to when they're getting ready to go back on tour would be perfect. It could be a little awkward between Brian and Nick if they haven't talked much, and yet, I hope the experience will be a catalyst for them to move forward in their relationship. Hopefully it will make Brian realize that life is too short to keep living a lie; he needs to come out, dump Leighanne, and try to win Nick back. And hopefully Nick will realize he can't live without Brian and fight for him, regardless of what Leighanne might do to try to ruin his reputation. That's what I would love to see happen, anyway!
I'm not sure how much more you have planned, but I think you can finish it in one long story. Who cares how many chapters it is? There's a feeling of accomplishment that comes with finishing a long one. I'm also not a big fan of sequels, but that's just me. I would only do a sequel if it seemed like the story arc of this one was winding down and you had a completely different story arc in mind for a follow-up story.