Muscles! Or lacking them!

I've talked many time on here about the importance of strength training/weight lifting.  It totally reshapes every part of your body.

When you look at 2 people of the same height weighing, say, 125 pounds, they can look RADICALLY different from one another depending on their muscle mass.  And looking firm and tight compared to "skinny fat" is MUCH more appealing to me!

Now I've been lifting for a while now, and have some pretty impressive muscles, if I do say so myself.  My calves are really defined from both running and weight lifting.  My biceps look good and I have some great shoulders.

However, I have almost no muscle definition in my back!  See?

Despite working my back, I have very little muscle definition in my lats and delts.  I do most of the exercises that they call for to increase muscle mass there including deadlifts.  

Apparently one of the ways to increase muscles back there is doing pull-ups.  While I can do chin-ups without assistance, I can't manage to do even one pull-up.  For those of you who don't know, in a chin-up, your palms face you and the biceps are highly involved.  In a pull-up, your palms face away from you and  the back muscles are more involved.

Here I am doing a chin up - palms facing - I can do a few of these from a dead hang.

But I have to use a ball or something else to give me assistance to do a pull up.











I guess I will try doing some more pull-ups with assistance, but someone also told me that, like the abs, muscles in women are harder to define until you lose more body fat percentage, and I'm not so sure that I want to lose any more body fat....