T.
I couldn't help but notice that you kept saying we. Would it be possible to have your partner take over? My 19 month old never slept in his crib, nor did his older sister. But at around 18 months we wanted them out of our bed. With the first child it was because I was 5 months pregnant. Logistically, I don't think we all would have fit in our bed. Anyhow, now with number two we wanted him to sleep in his own bed. It's a toddler bed so he can get in and out of it.
My husband took over the bedtime routine. Everytime he got out of bed, my husband would remind him to go sleep in his own bed. I was totally out of the picture. I would stay down stairs until he was asleep, and I would stay in bed and let my husband handle him when he got up looking for me. It only took a weekend to get him used to it, now he stays in bed until almost 6:00 am. Anyhow, it was much easier to get him used to sleeping on his own, without the distraction of mommy. We are also working on weaning, so there is also that distraction.
I suppose what I'm suggesting is to try to let someone else get him used to sleeping on his own. It doesn't take long (sadly) for them to get used to a new routine without us.
Good luck,
T.