I don't know if anyone else has touched on this but I know from experience that my beard continued to grow and fill in through the years. Everyone is not the same but I hear that new beard growth will grow in the 30's, 40's and even 50's. I had a space missing between my sideburns and chin hair and it filled in over the years. It's not as thick but at least the hole filled in. But with where you are right now in time, I wouldn't get discouraged at 13 weeks if you're not satisfied, I would shoot for 4 months because I have seen a dramatic change from a man who's sides were crazy patchy and he went on to grow a really nice big beard. He's on Youtube if you want to check it out.