Hi, I was having the same problem up until a few weeks ago! My son will be 10 months in 4 days. He started this behavior around 6 months and would go almost entire days without nursing at all (happened 2-3 times). What finally worked was something that I always read NOT to do when it comes to breastfeeding and that was a schedule. I also started giving him 10 oz of formula a day (my choice, not pushed on me) in a sippy just because I was really worried about his extreme slow-down in growth between 4 - 9 months. He's never been a great nurser but he just got to be AWFUL at about 6 months... like a mild nursing strike at least once week! :( That's why I finally started w/ the formula at 9 months. That stuff is NASTY but at least I know he's getting the extra calories that he needs. And at this point he's eating a bunch of solids so his digestive track is getting used to many things besides breastmilk anyways! Believe me, I TRIED so hard and I followed all the advice on message boards and kellymom.org but to no avail. We bf'ed exclusively for 6 months so I feel good! (okay enough w/ my formula guilt trip ranting...)
My son only nurses when he is tired as well so now I nurse him 4x a day - when he gets up (cause he's SUPER hungry, he STTN from 7pm - 6:30am), before first nap at 9, second nap at 1, and when he goes to bed at night. He drinks about 3 oz of formula 4x a day as well. He eats 3 jars of food a day and also has a tiny snack of Happy Baby Puffs and a little bit of cheese or veggies or whatever I have in the fridge.
The other thing I do every time I nurse is switch back and forth. My son will almost never nurse for longer than 2 minutes at at time so I make sure to do each side at least twice during all of our daily nursing sessions.
For my son he just needed the routine. Now he doesn't squirm and try to get away b/c he knows it's time to nurse and go to sleep. He actually nurses a lot better now and for longer times so it worked for me!