Does anyone have any suggestions for how I can tighten my lats without making them wider? When I look for info online about working out lats, I come across mostly bodybuilding sites that are, of course, interested in making the upper back broader. I have a very "inverted triangle" sort of body type already, and I don't especially like the look.

I noticed recently that the area behind my arm pit--kind of a weird way to describe it, but I think it's accurate--is flabby. In other words, it's the area where the side of my bra band and my bra strap meet. Are there exercises that can target this area without making my back wider? I've been doing occasional pull ups with my trainer, but it's occurring to me now that pull ups might be making the situation worse by bulking me up.
In search of a lost signature...