Not knowing if this is for a typical fantasy world or not, but unless your rivers are too small to show, towns and cities need to be located near water. So either place some more rivers or distribute your cities only where there is a river, lake or coastline (which you have already). While villages can survive with just a well, cities and towns need much more reliable water source.
It might help to use a vector application like Inkscape, Illustrator, or Xara to draw your rivers instead of doing so in Photoshop. You can create shaped lines that diminish to a point instead of an equal width painted river using a standard PS brush. Make your rivers wider - they don't look weird.