It's a 5k. It hurt like hell...then I tried to pick it up. The end.
"I think I've discovered the secret of life- you just hang around until you get used to it."
A Saucy Wench
I have become Death, the destroyer of electronic gadgets
"When I got too tired to run anymore I just pretended I wasnt tired and kept running anyway" - dd, age 7
You've got plenty of time. For at least 2, counting the one you did today.
Personally, I like my last long run a couple weeks out (or sometimes even less). I just take that run pretty easy - and generally make it 18 or so. I've done long and really long runs just 6/7 days before a marathon without a problem, as long as they're easy.
So if you want, you could do one (or two) more like today's. But I don't really think you have to worry about it, to tell the truth. Your training has been so consistent and your mileage buildup so steady, that I wouldn't worry about the long runs. (Yeah. I know. People like to argue the point.)
If it were me, I'd maybe do one more 18 miler, with a little MP mileage at the end. And focus more on your tempo and MP runs (which it looks you're already doing), maybe do a couple mile interval workouts (8 x 1 at slightly faster than MP, or something similar).