Is my ball python underweight or overweight?

[Moose84]

I’m currently feeding her one medium mouse every other week because she slightly had the physique of the middle (overweight) python in the picture. She eats readily but hasn’t pooped for a couple weeks and it’s worrying as in that time she at a clump of sphagnum moss.

She is being underfed. She should be double that weight if not more. A medium mouse is waaaay too small as well. By 9 months all of my animals are on small rats and 500+ grams. She should also be fed weekly as well especially if she was being given mice. The animal isn't passing anything because it is using everything for nourishment. I haven't heard of snakes eating moss but in this case it wouldn't surprise me because unfortunately she isn't being fed appropriately. I would go to weaned rats every week for a month and then move her to smalls.