I've only now just seen this thread and I'm very sorry for what has happened to Willow. You have shown a great deal of dedication and love in caring for her and I'm sure that's why she has made it this far.
I'm sure you feel much guilt and sorrow about what has happened but we all know it was completely an accident - something which could have happened to any of us.
From looking at the pictures, using my experience in many years of caring for kittens, I can see that she is very ill still. I know she has improved from just after the accident but she really, really does need to see a vet ASAP. I know money is an issue for you, as it is with many of us. Is there an animal shelter or rescue that you could give her to? They may be able to give her the x-rays and tests she needs and most importantly, get her to a vet. There is also a really good article here about what to do when you can't afford a vet: http://www.thecatsite.com/Health/76/...erinarian.html
Remember that cats and even kittens are very good at hiding their pain and I believe she is still hurting. She can't do much for herself right now and needs you to make sure she is getting everything she needs, including an assessment by a vet.
I would hate to think there may be something very wrong with her brain or other internal organs, causing her to suffer in pain, and we do not know it because she hasn't seen the vet again.
I will be honest here and ask you that you don't let your guilt about this accident, cloud your judgement in knowing what is best for Willow.