You should be fine with that kettle, I have the same size and can easily do 10ish pounds of grain w/o sparging. Last weekend I had to sparge for the first time, 13#. I still ended up w/ a 69% efficiency sparging w/ 80ish degree water!
Like the poster above said, just make sure you can support the bag of wet grains, I use a hook/pulley to support the bag and squeeze the wholly he'll out of it. So far I have brewed a Blonde and a Kolsch and the blonde turned out great and the Kolsch is happily fermenting away.