Your paddle might be a little short. An 8.5 is a good width, you might just work some on technique. Here's some things to try.

Don't paddle with your arms, they should be straight but not locked. You paddle with your shoulders, pushing down with the top hand. Bend forward some as you put the paddle in and bend your knees a little, get the blade all the way in the water and start moving it a little before you put the steam to it. You want the paddle completely covered with water. Pull back hard to just your feet, and as you get close to your feet rock your weight up, straightening your knees and pushing the board forward with your feet. Let the blade glide back but don't put power into it once it passes your feet. The shaft should be as vertical as you can get it, and the blade should be half under the board with the shaft nearly touching the rail.

If you watch the really fast canoe paddlers you'll see that they take short strokes, pulling just back to their knees, but they paddle fast and smooth. Some of those guys just fly in sprintsand distance racing.