hang in there - it was 6 weeks before I had my sleepy munchkin off EBM and back to mostly suck-feeding. Try and avoid the top ups as much as you can - feeding again (even if its only half an hour after you fed) is a better long term option.
Wanting to suck again isn't a very good guide to hunger in tiny babies - it can mean everything from tiredness to hunger to a stuck fart. A much better guide is wet nappies and pooh (at least daily for the first weeks). And a period each day (sometimes for a few hours) of wanting to feed constantly is a babies way of increasing your supply.
hugs.