Cities and Knights: Played to virtual deadlock
Let's see...

5 settlements 5VP
4 cities =8 VP 
Longest Road = 2VP
Metropolis = +2VP (above the city it's on) (3 of them).
2 1VP progress cards

6 Defender of Catan VP's as well.

There is a progress card that allows removal of an opponent's knight. Time it for just before the barbarians, and make him pull one, then you get your VP for Defender of Catan.

Remember - Defender of Catan is earned for there being enough knights... and being the man with the most strength when that happens.

If you have misplayed so that your cities and settlements are more than 2 apart, then you've simply played poorly. 

It is possible that, through particularly poor play, you might be stuck at 13 VP; if all the VP cards are out, and you're out of spots to play, it is time to call it, and I'd call it a double loss. 

I'll note however: The Fishermen of Catan does not increase VP to win (unless you hold the old boot), and the Harbor Master variant only increases VP needed by 1.