When you say you are walking straight, which direction is straight? Are you walking towards the 10pin or square to the foul line?
In all of my shots, I am square to my target line, not the lane. My push away is the start of my swing, has to be along the target line to keep accuracy in check. Start the ball on the intended line of projection and it will be easier to keep it there.
"...do or do not, there is no try."
St. Louis USBC Sport Bowling
Best Bowling Pro Shops Inc., St. Louis MO.