If you didn't have a centile chart, would you think there was anything wrong, OP? Does she seem well and look well? My DS went from the 75th centile to the 0.4th in the 1st 6 weeks, but after that sort of bounced back (on the 90th by 6mo check).
We were ebf and had struggled a bit, specially because I was labouring under the impression (Baby Whisperer, anyone?) that the baby should have a big feed every three hours, and occasional sucks were the 'baby using me for a dummy' (wtaf? Boobs aren't dummies, they are the real things that dummies are dummying? Anyway.). At the 6 week check, when he'd gained only a tiny amount and was going through a growth spurt (which terrify you on the best of days) I went into a panic, posted loads on MN, got a load of conflicting advice (RL and MN)...
But in the middle of it all, I thought, hang on - if I'd never had this 'advice' - books, etc. and I hadn't thought baby should be feeding in this pattern, and hadn't thought he shouldn't have occasional 'comfort' sucks so given him a dummy - basically, if he and I were on a desert island with no centile charts, I would just be following his lead and I wouldn't think anything was 'wrong' - fundamentally with him, or with his feeding pattern, or with his 'comfort' sucking, or with him having three short feeds one afternoon and one long one the next... and the only way I'd have of seeing that was anything wrong would be paying attention to him. He seemed fine to me - it was other people's beliefs and expectations of how he should be - how often he should feed, how long it should take, how much sucking he do and HOW QUICKLY HE SHOULD GAIN WEIGHT that were doing my head in.
My advice, ha ha, would be to ditch the advice - your baby will tell you what she needs. If you think your baby is fine, then the centile chart is wrong - IME weeing, pooing and general disposition are what to look at. Of course, if you don't think the baby is fine then chase really hard like the other posters have said. But otherwise, trust your baby to communicate her needs and your ability to meet them. You will not be doing any harm by following her cues - ignore anyone telling you you have to 'teach' her to sleep through, or settle herself, or take x amount in x minutes at any given feed. She knows if she is hungry, is tired, etc.
Good luck