My first dropped all the way to the third percentile for weight and was a voracious eater. She popped back up to around 50% at 15 months. My third had horrific GERD and once that was covered with medications gained fine. My second has always been big. Ugh, each is so different!
She has a wet diaper every time she nurses and we just started solids tonight. She actually has not yet been noticeably sick...maybe a slight runny nose once. She is incredibly happy and content, very verbal, working on sitting, been rolling both ways since before four months, starting to scoot forward now...maybe she does need more calories. Solids were not a hit tonight but since she has never had a bottle I can't really supplement that way (I don't get milk when I pump but have also never had to supplement).
I am really working to stay very hydrated and will add oats in the morning I think for me and her. I did lose 12 lbs during her fourth/fifth month and maybe that was not a good thing. I'm still up 18 lbs, though, so it wasn't a scary weight loss this time.