I have the same problem. Huge upper body, but lack the "V".
Some people ask me whether or not I do my rows, pulldowns, and pullups, but of course I do! What dedicated bodybuilder just skips workouts? But, as my personal trainer friend just pointed out to me a month ago, I have been doing them INCORRECTLY for the last five years! And its a habit. The wrong way is ingrained in my head this way. He talked me through the correct motion at the gym, step-by-step, and sure enough, I actually felt my lats working for the first time in my life! It felt great when I put my roll-on deodorant on after my post-workout shower. I could feel a huge difference. I was using my traps and lower back before instead of my lats!
If you live in NYC, I can give you the name of my friend and his contact info . He is, by far, the most knowledgable person I have ever met about good form. I still have problems doing it right when he isn't around, since my brain is really trained to do it wrong all these years. But lats really are critical for upper body width, and I am putting a lot of effort into it now. In a nutshell (for all pulling movements) -- keep your traps COMPLETELY RELAXED, push your chest OUT FORWARD, and squeeze the shoulder blades together as tight as you could. Lead with your elbows, as if there is a straight arrow pointing from your elbows in the direction you want to bring the bar. Get a full, controlled negative (like everything else), keeping the traps relaxed during this part of motion.
I hope this helps you.
Remember, when your back is facing them is the only time chicks can stare at you without you noticing. You want huge lats!
--Fellow narrow latted guy