Faye,
Michele's experience is a lot like mine...however, my son night weaned himself at 13 months old and hasn't needed anything but, a cup of water by the bed. I too, have chosen to co-sleep with my son but, he goes back and forth between my bed and his bed, and I don't feel the need to pressure him to stay in one place or make it a big deal. But, to your issue...
While it may seem awful because nobody is getting a 'good night' sleep it's just a conglomeration of phases and changes to the 'norm' that your son needs help getting through. Your son may be experiencing seperation anxiety, teething, night terrors and/or just not feeling good. It's all normal for the age/stage and can be very daunting to deal with at night.
I don't think nursing to sleep is a 'habit', I think its a beautiful way to comfort and take care of your child when they need you. I fed on demand for the first year with my son, and it always changed depending on his needs for growth and development. I have been very lucky to have a Pediatrician who endorses this, and even encourages going with what works for you as far as sleeping...in my opinion Ferber is a great method for those who can use it properly. But, with new studies about Cortisol and the development of the infant brain, I just can't abide by letting a child cry. That's just me though.
When my son was 13 months old when I went back to work, not by choice, and had to put him in childcare. Like yours, he got sick constantly and was miserable...multiple ear infections and no sleep. He wouldn't nap and just looked awful when I picked him up at the end of the day. So, at the suggestion of my son's Pediatrician I found someone to watch him at home, and now pay my Mom to take care of him while I'm at work. It's great because he gets constant one-on-one care and he gets to be at home...my son just didn't adapt well to the environment.
My best suggestion is find consistency of routine, and stick with it. Make sure whatever your bedtime routine is that you stick with that every night, no matter what. Talk to your daycare provider and tell them what your routine is and what nap schedule you'd like your son to follow and they should be willing to help you with that. Also, don't worry...our kids feel our stress and can display it in the same ways we do...lack of sleep, anxious and cranky. My daycare provider was great and the infant care people were very sweet, it just didn't work for us and I had to come to terms with that.
It will take time to get past this phase, but you can do it. Change is not something infants and toddlers do well with, and when MAJOR changes happen this can cause a meriad of issues...don't blame yourself! You are a great Mommy for breastfeeding and doing what you can to make your son happy and healthy.
If you want to night wean him now, it's going to take some time. My son did it on his own, but when he'd get sick we'd go back to one a night for comfort and to get him off of it, I'd have to follow the same routine. Go to him, cuddle with him and rock him to sleep. Explaining that Mommy was there and it was okay, after a while he was able to sleep without the feeding but, my son was much older than yours.
No matter what advice you get, I think the one thing I can tell you from my experience is, go with your gut. There is nothing like Mommy Instincts to tell you what your child needs, and what you should do to meet them. Follow your heart!
Best wishes to you and your little family.
Great article and resource...has info from Dr. Ferber
http://abcnews.go.com/Health/story?id=4263379&page=1