Use a prop, in this case Yamuna Gold ball to lift your hips higher which can help to bend you to fold from hips, rather than lower back!
Stretch out your legs wide, either straight or bend...listen to your body here.

But the main reason why I use the ball is that simply sitting on ball helps to start addressing the pelvic floor and the ball starts stimulating the bone tissue (body of the pelvis) and insertuions of inner thigh muscles!