How to force system to previous page

I have a file that's 18 measures long with three staves: vocal (with lyrics), guitar (treble clef), and guitar (tab staff). I'd like to arrange it on two pages, with 3 systems per page and about 3 measures per system.

That wasn't a problem at first, but once I started adding multiple lines of lyrics (there are three lines of lyrics), things started to get difficult.

The default vertical spacing between each line of lyrics was way too much, so I figured out a way to adjust that. When I finally got the lyrics spaced out the way I like, the score had been stretched out to three pages for some reason. I was able to get it down to two pages again, but the layout is not the way I'd like.

Now there are only two systems on page 1, and there's lot of space at the bottom for a third system there, but I can't figure out how to fill that blank space.

I've attached the file.

Thanks!