You could try a shorter paddle, and practice paddling with the blades as close as possible to the boat by holding the hands higher. This isn't as tiring as it sounds if the blade enters the water well ahead.

I have a similar kayak 9' - 5" long, it is better than most others I've tried but has one fualt. Like many of the breed the max beam and cockpit are well aft. It glides well but the stern soon starts to slide off to one side or the other and the boat goes into a turn. A rudder solved the problem. A skeg would have done the same but in the narrow streams I like to explore the rudder is useful.

I couldn't find a Dimension less than 9' long . . . it might be an older model.

If the kayak wants to run downwind all the time (windsocking) attached a small, stiff flag or other flat material at the bow; adjust the size until it balances.