girth is strange. At first most gains for me were in length, now my gains are mostly girth. just be dedicated to doing some kind of Pe, even if you reduce your work out at times. The main thing is to keep doing pe and the gains will come.
also set some goals. Not specific size goals, but rather i will gain something in the next set of work outs. i would say to myself, "I'm going to do this for three months and gain something."