Some concerns about my favorite Hen :(

[MissLavender]

Little Kali the Ameraucana has always held her tail a little lower than the other birds. She is two years old (according to the breeder), and at the bottom of the pecking order. She is the smartest, sweetest, most inquisitive hen out of the eight that I have. I have never seen her lay an egg since I got her in September with the rest of the flock, and her comb has always been kind of pale. She is active, eats and drinks, poops are normal, no symptoms of illness. So I guess my question is this: is her tail carriage something I should be concerned about, or is she just submissive?
Also, she's in a soft molt, so you can't really tell she's molting at all unless you lift her feathers. Then it's more obvious, ie: new feathers visibly poking through underneath.
I picked her up last night to check her out...her crop seemed a little watery, with some food and stuff palpable in there, but then again she was eating snow ALL DAY so that might not mean anything. She is, however, alarmingly thin. Her little keelbone is sticking out like a knife blade. I checked her vent, it is small and dry like a pullet who hasn't started laying yet, bones are very close together. No fluid on her abdomen, no obstructions. No sign of mites or lice from what I can tell. I am giving the whole flock a course of SafeGuard dewormer since they're about due anyway. Every time she tries to eat from the feed bin the other hens chase her off if it, so she has stopped trying. She will eat from my hands with enthusiasm, so I know she has an appetite. What else can I do for her? I appreciate your help!

 

[azygous]

This has the sound of a young hen with a victim complex. Don't laugh. This can result in death from starvation.

Your description of her as being at the bottom of the pecking order, signs of being very underweight, pale comb, and delayed fertility all add weight to this hen being starved away from the feeder.

What happens is an individual starts out with a very docile temperament. They are not inclined to compete for food and are easily discouraged from standing up for themselves. Eventually, what results is a hen who has learned from the others in the flock that she isn't entitled to food, and she gives up even trying.

To change this dynamic will require a few weeks of special handling, although it's not as hard as it may seem. Here is an article I wrote to help chicken keepers rehabilitate such a timid hen that believes her normal role is as a victim. https://www.backyardchickens.com/articles/chicken-bully-chicken-victim-a-two-sided-issue.73923/

In short, you will be giving her special protection from being bullied in order to retrain her to see herself as worthy to eat as the others do. She will spend days alongside the rest of her flock but in a safe enclosure. At night you will put her in the coop with the others.

This process of restoring self confidence can take as little as two or three days or as long as three weeks. The transformation will be quite startling and will be long lasting.

To rule out a crop disorder, which sounds like a possibility, check her crop first thing in the morning before you give her any food or water to be sure her crop is completely empty.

 

[ChickNanny13]

Oh my, she's so pretty It's obvious she's being kept from the food/water, eating only the snow she's starving. PLEASE follow azygous advice ... You could also add more feeders/waterers, maybe make a special area she can eat in peace.