Solidstars - I can`t say it`s always obvious when the baby is done, but the advice I read is to let them suck until they go off it themselves. When I know my baby has had a really good feed is when he lets go, and does this fabulously cute stretch and then when I`m burping him he looks completely out of it. Like a drunken sailor, as someone noted before.
In my early weeks, I had no idea how much my baby was getting - he just sucked and sucked and I tried to get him to switch breasts and timed our sessions and all that. And sometimes it took forever.
Then it got better. And also I relaxed a bit and just followed his leads. I definitely favour feeding on demand, particularly with a small baby, because they are too young to manipulate or `want` things. They want to feed when they are hungry, and that`s that.
I read - and I don`t know if it`s true - but I read that the main milk flow from let-down only lasts for 20 min and after that it`s more comfort sucking. But I think the baby might still be trying to get more milk if he was not satisfied.
I know, it`s so hard to tell right now. But have him weighed and that will be the best indication. My boy came out at 2.9 kg and at one month he was at 5 kg so I knew something good was coming out of my breasts, hehe.