To the OP's original question, at least as I understood it, I think that generally the title of the song should be found somewhere within the lyrics of the song.

Not always mind you but most of the time that's how it works.

Generally speaking the title is the one line of the song that haunts you and becomes unforgettable and is usually, at least in the vast majority of hits as far as I can tell, the main line of the chorus.

The title most often contains the theme to a certain extent.

So if you write a song and you can't figure out what you should call it, then I think in many cases the song doesn't have a theme yet and the chorus probably isn't right either.

Of course this is not true for all songs and it's not true for everybody but it's definitely true for me.

If I can't find a good title then I realize I probably haven't written the song yet.