Hi Gabrielle,
I don’t have any trouble with Janushirashana. My knees are locked and I am able to lift my heel and touch forehead to knee. In second part of posture my back is slightly rounded because I am a little kyphotic. Again my legs are straight amd I am looking straight ahead. I feel the stretch in my hamstrings until teacher gave me a little pressure on my back. Then felt more stretch in calves