Part of the issue may be that a typical baby pooh-and-wee-and-feed can cause a difference of a couple of hundred grams between (just fed, haven't pooed and haven't weed yet) and (just pooed and weed, haven't fed yet). Can you weigh her again in a week or two and see if things have changed? Also try offering her feeds at least every couple of hours during the day - and maybe try offering her the first boob again after she has finished the second.