Both of mine have been doing very long blocks over night at 3 months, often 11 hours - never had a supply issue. With DD I did hand express occasionally in the evening, but with DS I don't do anything. If he wakes I always feed him but it is rare - I think he made up by cluster feeding in the early evening and is prob every 2 hours ish in the day. He has always been super keen first thing in the morning. I would assume it is always to do with how efficient they feed, my two are obviously like me - shovel down as much as you can as often as you can as fast as you can :-) - and not sure whether pumping is of the same efficiency - so I would definitely chat with a LC to check but I would have thought you should be able to get a longer block even if that meant extra pumping in the day (although this could mean you get woken up by your BB's because you need to express - but I would think this would be better for sleep cycles than being woken by an alarm).