I agree that switching to a triple would be a mistake. First I would ride it as is and see if the current gearing really represents a problem or not. My guess is that it won't.

If you do want a wider range, the suggestion to get a different cassette is a good one. If that is not sufficient I would suggest a compact double rather than a triple. They are becoming much more popular on road bikes and saves you from having to replace your shifter and rear derailleur.