What we're trying with our 14 month old (well, we'd started trying it then teething cropped up again so it's been slow-going of late):
Let her choose a lovey, since she doesn't have a preferred toy or blanket. And wouldn't really accept one when we tried to press it. So now she's old enough to choose one for herself! We put all the little lovey type toys and things in one place and let her pick and choose each time before naps and sleep. Each time she'd make it clear which ones she wasn't interested in, so we've reduced the pile each time, removing ones she doesn't want. So now it's down to two toys (both Under the Nile dolls -- she's got good taste hehe), and one blanket.
Everytime we nurse, she has the blanket and one of those toys (I let her choose). This is so she'll associate those items with the comfort of nursing.
You could also use one of your tshirts or something that smells like you -- just make sure it won't get tangled up in your child while sleeping.
That's so the baby associates a state of comfort -- a smell or tactile sensation -- with nursing, Mama, and sleep.
Our problem isn't getting her to sleep it's getting her to stay asleep. And she won't take a pacifier, so our choices are either human lovey or toy/blanket lovey.
Right now she naps in the papasan swing still, and the motion soothes her if she stirs. At night we co-sleep so if she stirs, I soothe her. What we're working on is helping her learn to soothe herself when she starts to wake so she'll go back to sleep without it requiring nursing.
I'm trying at night not to soothe her immediately myself, but to put the blanket in her hands and see if that will trigger a comfort response. It's very slow-going, but we were making good progress until the teething kicked in again.
We've read the No Cry Sleep Solution which has some good tips in it, but have had to adapt some of the solutions in it.
Our main problem is that she had dropped %ile-wise slightly last ped appt and I felt guilty so started letting her nurse all night again. That was a BAD idea. So now we're back to where we were around 6 months, with her needing to nurse while she sleeps. There's a difference between nursing to sleep and nursing during sleep. So we're trying to use the pull-off/unlatch method once she's asleep. It's very frustrating, but slowly but surely it'll work, and we'll have her napping -- and staying asleep -- in the crib at some point soon, I hope.
Early on we designated the nursery as the daytime sleep room and our bedroom as the nighttime sleep room. That helped a LOT too. And using the same routine everytime before sleep helps too. But like I said, the issue isn't getting her to sleep -- it's getting her to stay asleep. Once they get really mobile, they "practice" in their sleep a lot, so for us, it's all about finding a way to help her learn to soothe and settle herself without it involving my boob.
When she was itty, I had no issues with nusing her to sleep and in her sleep, but at 14 months it's getting really hard and draining for me to continue it nonstop. So I feel your pain and wish you luck (and please keep us posted if you find a solution that works for you!).