I've recently taken up yoga, been going twice a week for about 4 months. I feel like I am not progressing, there are things I can do fine such as most table top and warrior, OK with balance. What I'm struggling with is a lot of work on my back and sitting, I can't cross my legs even on a block, I can't do child's pose, eye of the needle and can barely hug my knees. I appreciate that not everybody can do everything and it is about your own ability, but I would have thought I would be getting better. I am quite short and have short arms, is it ridiculous to think that this may not be helping?