I assume since she was gaining weight before that you know for sure she was latching on properly to be able to feed fully. But as Jenny mentioned she might be needing more about this time, so any lack earlier might have been less noticeable.

are you drinking plenty is another quite obvious possibility of course... have you been drinking less recently for any reason?? You shouldn't run low on milk unless she's not feeding properly or you aren't drinking enough.

and if nobody has put you onto them before try contacting www.lalecheleague.org - they might be able to come up with something nobody else has thought of. You should definitely try to hang in there with the breastfeeding first, as frustrating and exhausting as it has apparently been for you. Once it's gone you don't get it back and I have that regret with both of my kids.

the only trick I know with the bottle is to make sure there's some breastmilk on the bottle nipple so she recognises the smell, because formula is not the same smell.

Kerri.