Hitting the wall?

On the edge of my first half marathon (next Saturday), I feel like my get up and go has gotten up and went. My milage this week is shaping up to be very sad indeed. Didn't do my long run the past two weeks in a row, both because of timing issues. This seems to be a crucial problem for me - go too early in the day and I'm still tired, too late in the morning and it gets too hot, too late in the evening and it gets dark on me. It's just so hard to fit it in with kids and dinner and other things I need to get done during the day. And I want to make running a priority because I enjoy it, but I have so many other priorities already, how can I really put anything else up at the top of my list? And I know another part of the problem is that I've been staying up much too late at night, waking up multiple times with the kids, and I'm just exhausted. No wonder I'm ready to throw in the towel after 3 miles, I'm just absolutely beat! My pace isn't suffering all that much, though, which is nice, but jeez, I need to figure out how to work things better so that I have time to run, time to sleep, and time to do everything else I need to do in my life.