I use to have the same problem... I was limited by equipment at my work's gym, I found when I joined a real gym and kept forcing myself to up the weight on leg presses, my legs improved. Then I tried squats, again always pushing to keep putting more weight on the bar, and my legs got much, much better.
I think the moral of the story is just use more weight, your legs can almost always move more weight then you think... dont get hurt though