I usually use bias binding and I have baste the raw edges together with a narrow longish zigzag stitc. Length set at 3 ansd width set at 1 about 1/ 8 inch from the raw edges.
I do not press the binding in half either - because the outer layer has to " go further" than the inner layer.
Think about how the wheels track when making tight turns. The wheel on the outside of the turn has to cover more distance than the wheel on the inside of the turn.