Where is your sticking point? Does the weight stop half way up, get pinned at the bottom or stop towards the top?
Like Liquid said, you row, your legs are stronger than the rest of your body. So make sure you consider that.
I would post a video. Your form may look good to you, but the angle you see isn't all that great. I used to have issues with forearm angle, and couldn't see that. Post a video and let us critique it.
Also, how much can you: low cable row? Weighted pullup? No offense, but I've seen rowers w/ bad form and not-so-strong backs (how? idk...) I figure I'd ask while I'm at it. I've noticed, and read here, that the row/pullup is about as much as you -should- be benching, which holds for me.