Nursing to sleep?

Lindsay
When did your baby stop nursing to sleep and fall asleep independently? 
Here's my scenario: babe is 18 months old and nursed to sleep for naps (when I'm home and not working) and always nursed to sleep at nights. She sleeps at minimum 6 hours straight, eats and then back to sleep. Naps are so/so- some days we can only get 20 minutes and other days 2.5 hours. I would love to have her fall asleep independently but I don't know that I'm ready to sleep train. Also don't know that I'm ready to give up nursing to sleep. Tell me your stories!