Interesting what you say about fast flow teats BAL because generally fast flow makes them drink more because it's in their belly before they realise it's full!
That's probably the idea with my little one, he's having top ups because he's not putting on weight so we are trying to get as much into him as possible. Also my milk supply was crap there for a while I didn't want him to concentrate on the bottle and realise that's where his food is coming from so he has a breast feed, bottle then breast.. Hopefully he associates the full feeling with being on the breast.