It's really not about adding one or two exercises, but an overall strategy to get things back in balance and keep them there. Remember that sitting, typing, reading, text messaging, driving, cooking, watching tv, etc. are thing that encourage poor posture and will lead to the lack of development that you seek. So, keep watching that, because say you spend 8 hours a week in the gym... How many hours do you spend doing those other things that take you backward? Gotta keep that posture good because it effects what your back can do when you're back in the gym.
Like Kuri says, get the volume up on the pulling exercises and keep it there. Shoot for twice the volume of pulling to pushing. In addition, it's important that you do mobility exercises to activate your back first. Wall slides, Prone Ys, facepulls, scap pushups, etc.
If you really feel like your back is lacking, keep going with pullups, chinups, and the seated rows, but I'd give the BO Rows a break for a while. Concentrate on lifts where you don't have a lot of other things going on (holding your back in a safe position, not cheating to row it up, etc.). Save them for later. Add in some inverted rows to replace them on a horizontal pull day.
Finally, for those rear deltards, try some cable
rear delt raises. It's part of "do more pulling" anyway.
BTW, I just started doing some ISO Seated Rows a couple of weeks back. Brutal!