Your hips need to be square and your legs straight out in front and behind respectively. Sometimes when you push down from a lunge your legs start to twist out a bit as it is easier for them to move in that direction so you may have to adjust them. Try to sit upright in your splits. If you are 6 inches off the floor you will need to prop your hands (e.g. on yoga blocks or stacks of books) to do that.
It helps to warm up first and do some preliminary stretching like knee down lunges and pigeon pose.
When you're on the floor comfortable...you're legs should be straight and your feet stretched to a point...that's how I used to do it anyway
Keep stretching as much as possible
Your hips need to be squared and even with each other if that makes sense.
Your balls hurt
