I agree that I think you and your dh have to decide what situation you'd like to get to and move towards that. So if you want her in her own bed, then I'd start a new routine with that as the end and make a big deal out of it - get her excited about having her own bed. If you plan to continue breastfeeding, then make sure it's not part of the going to sleep routine -have it before bathtime, for instance. At 20 months, she probably doesn't need the milk right before bed, and if she's thirsty, then water would be fine or something else from a cup. She's not too old to get attached to a lovey at all - involve her in the process. I would give my daughter a choice of stuffed animals and I ask her which she wants to sleep with.
You said, though, that you're happy with her in your bed. Then I would focus on teaching her to fall asleep there on her own (or as Kate suggested - in her bed, then move her if she wakes overnight). Routine is really important though. It will be harder to wean her from night feeds overnight in your bed, but it's not impossible. If she could sleep on dh's side of the bed, or if you wear a non-nursing bra to sleep, it'll make the access harder.
I would also suggest that you coincide having other soothe to sleep methods for naps while you do this. It'll help to be consistent. Nurse her earlier, so that she won't fall asleep that way. But DON'T GIVE IN! If you try something else, then cave in and nurse her overnight or for naps, then it'll teach her to hold out longer! Also, explain to her what you're doing. She's old enough to understand parts of it anyway, and emphasize the lovey.
Hope this helps! It IS possible to do this. I have a good friend who nursed to sleep for all sleeps and managed to break the habit at about 2 years old. They still co-sleep in the early morning.
