My 9 wk DD is also touchy, and we got her to sleep in her crib around 5 weeks. I missed the holding very intensely for the first couple days, but once you get used to having so much more free time, it's really nice. I also tried to remember how sore my back and arms would get from holding her so much - she was already about 12 lbs at that point.
She will still occasionally fall asleep on us, but I try to limit it to once or twice a week. Try to be really strict about it for the first week or two, then you can probably let her fall asleep on you once in awhile. But don't let her too frequently, or a few times in a row, or you will probably be back where you started.
Karma