How do you know when your breast is 'empty'?

[Imafairy]

Sorry - this is probably a very dumb question, but how do you actually know when your breast is empty? When I feed DS2 I know he is getting lots of milk at the start, but he always ends up dozing while suckling. I remove him and re-latch him after a while, but I'm never convinced that he's actually finished everything when he has finished, IYKWIM. His weight gain is okay, so I'm not worried about that, but I want to make sure that he's not just getting foremilk. Also, if he's not emptying it, then that's going to affect my supply, isn't it?
Any tips?
thanks

breasts are never empty only sometimes less full.

Breastmilk production works on supply and demand. Each time you breastfeed, you are stimulating them to produce more.
Into the feed, the milk becomes more creamy hence the terms fore and hind but they arent actually separate milks.

Basically, you sound like you are doing fine so just enjoy it and dont worry.