Qs for the sleep training experts...

I started sleep training DS a little over a week ago, I was amazed that by the third night it was a dream, he was falling asleep on his own, even in the middle of the night, and only waking to nurse twice a night, as opposed to every hour as it was before. After that it's been up and down, some good nights, some, more crying that I'm comfortable with, and I know in some occasion I have undone my own work.

Seeing how some nights are a breeze but others not so much has me wondering,

1) how do I now he doesn't need something else, hence the crying, like maybe he needs to burp, or has gas pains, or he is still hungry or wet (I felt so bad one night I let him cry for like 15 min and I checked him he was soaked! he had leaked out of the CD--an ongoing issue).

2) Since his problem was associating the boob/my arms with sleep some nights he still falls asleep at the boob and even though I try to do the sleep sack after as a last step in order to place him in his pnp awake, sometimes it's hard to wake him up so I end up putting him down almost asleep not awake enoughfor him to realize he's being moved.

Thanks ladies!