I night weaned my son at about 19 months because I was pregnant and couldn't handle the nursing at night. He continued waking once or twice during the night, but we co-slept also and I usually threw him over my shoulder, carried him to the bathroom, peed, and put him back down asleep.
We bought my son a twin sized futon and put the mattress on the floor in our room (we co-slept) when he was about 21 months. We went back and forth and gave up and just let him co-sleep with us and figured we'd deal with it when we had to.
Interestingly enough, when the baby came home, my son slept through the night for the first time willingly in his own bed, at 24 months exactly! He is 30 months and sleeps through the night about 4 nights a week and the other 3 he either comes to bed with us or we go to him (he's still in our room).
I guess I have no advice, but wanted to let you know that I think some kiddos just aren't great sleepers. My 6 month old started sleeping 8-9 hours a night from about 3 weeks on and we did the same breastfeeding, co-sleeping thing with him as with his brother. He's now teething and nursing a few times a night.
They are all different.
Maybe night weaning will encourage your youngster from waking? I was stressed and felt bad bout night weaning, but it was super easy. He asked once the first night, I said no, carried him around a bit and he fussed. That was it.
Good luck! You sound like a great mama!